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Item Behaviour of single-suckled Angus cattle from calving to weaning : a thesis presented in partial fulfilment of the requirements for the degree of Master of Agricultural Science in Animal Science at Massey University(Massey University, 1978) Aitken, Victoria RobinThe main objective of this study was the investigation of behaviours which might influence the number and/or weight of calf weaned from single-suckled Angus cows. The behaviour patterns involved were those relevant to parturition, the cow-calf bond and nursing. The effect of such factors as maternal experience, sex, and age of calf and the presence of non-lactating cows were also investigated. In addition, the liveweight of the calves was taken at birth and thereafter at regular intervals throughout the course of the study. Observations began on average 31 d (range 4 to 65 d) pre-partum and continued until 3 weeks post-weaning, c. 33 weeks after the start of the investigation and involved >900 h of field observations. Eighteen pregnancy-tested Angus cows were involved of which 14 calved. Of these,5 primiparous and 6 multiparous reared their own calf. Two calves, 1 born from a primigravid and the other born from a multigravid cow, appeared to die as the result of abnormal maternal behaviour. These maternal behaviours resulted in either physical injury to the neonate and/or refusal by the cow to allow the calf to nurse. The latter behaviour was followed by hypothermia in the calf, although adverse weather conditions probably accentuated this heat loss. Two primigravid cows rejected their calves and had to be isolated for up to 5 d and restrained before the cow would accept the calf's presence and nursing activities. A method of predicting the order and time of calving for each cow was devised. Determination of the calving order was possible in 12 of the 14 cows prior to the birth of the first calf. The use of 24 physical signs allowed prediction of calving time to within 48 h in all 14 cows. Changes in such behaviours as posture and social activity were associated with calving within the following 3 to 4 h in all except 1 cow. This animal was found to exhibit dystocia, i.e., an extended parturition of >19 h. On average the physical signs were observed before the behaviours and more cows were recorded for the presence of physical signs than for behavioural signs. However, there was wide variation in the number of signs recorded and the time they were first observed for each of the cows. No single sign could be effectively used for prediction of either calving order or the time of calving, i.e., delivery of the calf. There was a highly significant difference between the primigravid and multigravid cows in their calving time. The heifers showed a decided tendency to calve during daylight whilst equal numbers of the older cows calved during daylight as during darkness. The area chosen for calving did not appear to be random. A very highly significant number of cows calved in the same area which provided the parturient cow with visual isolation up to 20 m. The importance of such isolation and subsequent localization to a specific area on the early occurrence of nursing and primary socialization was demonstrated. Determination of onset and termination of first-stage labour on the basis of either physical or behavioural criteria was only an approximation. Overall, it was more difficult to determine the duration of the various stages of parturition using behaviours than when using physical signs, although there was a tendency for the different behavioural parameters to occur more frequently and/or at greater intensity at specific times during the process. The effect of experience on maternal behaviour was demonstrated on a number of occasions. For example, with one exception all the primiparous cows showed a significantly shorter duration of maternal grooming of the neonate than did the multiparous cows. With the exception of 1 multiparous cow, abnormal maternal behaviour was observed only from the primipara. Five of these 6 cows showed some form of agonism on first seeing the neonate. In all except 1 cow this ended several minutes after the cow had investigated the calf. Other abnormal behaviours such as orientation toward the calf during its teat-seeking activities were recorded only amongst the first calvers and on all occasions resulted in a longer time taken prior to location of the teat by the calf. On termination of the dam-offspring association at weaning the response from cows and calves was apparent in changes in their behaviour. During the following 7 d the calves showed a very high level of unity in their activities and spatial distribution. As well the form of social interaction changed and became predominantly agonistic. This resulted in rapid establishment of a social rank which appeared to decrease further agonisra and instead increased such epimeletic behaviour as grooming. Despite these changes in behaviour the liveweight of the calves did not significantly change from 11 d pre-weaning until termination of the study 21 d later. The cows reacted to weaning by increased aggregation, vocalization and walking for up to 9 d post-weaning. These changes were reflected in an apparent decrease in grazing and rumination duration. Fence damage and localized areas of severe pugging was also recorded. Nursing was investigated for the form and degree of occurrence of both maternal and filial behaviours, including cross- and non-nutritional nursing, as well as the pattern of sucking, i.e., sucking frequency, duration and time spent nursing, and the diurnal and circadian rhythms.Item A study of the growth and carcass characteristics of rangy and short type steers of the Angus, Beef Shorthorn and Hereford breeds : a thesis presented in partial fulfilment of the requirements for the degree of Master of Agricultural Science in Animal Science at Massey University(Massey University, 1979) Andrewes, Wayne George KempThe growth rate and carcass characteristics of rangy and short conformation types of steers in Angus, Hereford and Beef Shorthorn breeds were compared in two trials (Trials X and XI) at Massey University. Rangy and short type weaner steers were chosen on the basis of visual assessment of conformation by experienced stockmen. The Angus steers in Trial X came from the one herd as did the Hereford steers in Trial XI. The two types of Angus (Trial XI) and Beef Shorthorn (Trial X) steers were bred in four different herds. Types within a breed were chosen by the same people, but different persons selected the representative steers in each breed. The steers were grazed together at pasture (except for a short period on a wintering yard in their second year of life) and weighed "full" at various intervals. They were slaughtered at an age of about 30 months. They were processed according to normal commercial practice and various aspects of carcass yield, composition and data on carcass weight, grade, fat colour, and chiller shrinkage were collected, various carcass measurements were taken and the weights of fat and bone were recorded for the right side quarters of each carcass. Fifteen steers were purchased of each type. Trial X concluded in March 1976 (after a period of 625 days) with 13 rangy and 14 short Angus steers, and 14 rangy and 15 short Beef Shorthorn steers. There were no animal losses in Trial XI (633 days) which finished in April 1977 (with 15 steers in each type group) in which the two types in the Angus and Hereford breeds were compared. The results were analysed within trials by the fitting constants procedure using fixed-effects linear models. Type effects were compared within each breed group. One model included the right side of the cold carcass as a covariate for some aspects of the carcass data analysed within a breed. Rangy type steers in each breed had heavier initial and final liveweights and carcass weights than short type steers. Rangy steers grew more rapidly than short steers in three of the four comparisons. There was no significant difference in growth rate between types of Angus steers in either trial. Rangy Angus steers gained 0.02 kg/day (n.s.) more than short Angus steers in Trial X, but the short steers grew faster in Trial XIf 0.03 kg/day (n.s.) and they may have exhibited compensatory growth in the first half of the trial. Rangy Beef Shorthorn and Hereford steers showed a greater superiority in growth rate (Beef Shorthorn 0.07 kg/day, P<0.001; Hereford 0.06 kg/day, P<0.001), compared with short type steers of these two breeds. These differences are important advantages in beef production, however the large difference in growth rate meant that because all steers were slaughtered at the same time (to meet the experimental design) the faster-growing Beef Shorthorn and Hereford steers were carried to much heavier weights than would be normal in most farming situations and this adversely affected their carcass composition, because of higher proportions of fat resulting from their heavier carcass weights. An analysis of the order in which steers were slaughtered showed that they moved into the stunning box independent of their type, breed group or liveweight. This finding indicated that data collection subsequent to the processing of the carcasses or in the boning-out of the quarters would be spread across types and breeds randomly. There were very small, non-significant differences between types in dressing-out percentage, carcass shrinkage in the chiller overnight (by weight, or as a percentage of hot carcass weight), and between the weight of the right and left sides of the carcass. This meant that the types tended to rank in the same order if their mean carcass composition was expressed on either a right side, cold or hot carcass basis, or liveweight basis. Preliminary statistical analysis showed there was little difference between types in the distribution of trimmed, boneless lean, bone and trimmed-off fat between the forequarters and hindquarters of the right sides. Therefore the data for each quarter were pooled and the composition of the right side of each carcass was compared between types. Rangy steers yielded a greater weight of trimmed, boneless lean and bone in each breed group. They yielded a lower weight of excess fat in Angus steers, but not in Beef Shorthorn or Hereford steers. There were small, inconsistent differences between types in the percentage of commercially trimmed boneless lean and bone, but larger differences in the percentage of excess fat trimmed from the right side of the carcass. The size of the type differences was influenced by right side weight. The ratio of trimmed meat to bone did not differ significantly between types, therefore it was concluded that the main determinant of the differences in the percentage yields was the amount of excess trimmed fat. Rangy steers tended to have a lower percentage of excess fat and were leaner than short steers except in the case of the Beef Shorthorns and Herefords. Angus types had similar amounts of kidney and channel fat (no significant difference between types in Trials X and XI, respectively). Rangy steers had more kidney and channel fat than short steers in Beef Shorthorns (1.73 kg, P<0.05) and Herefords (2.22 kg, P<0.01). When adjusted for right side weight there was less kidney and channel fat in rangy than short Angus (0.72 kg, n.s. Trial X, 1.72 kg, P<0.05 Trial XI) and Beef Shorthorns (0.53 kg, n.s.), but slightly more in rangy Herefords (0.53 kg, n.s.). Rangy Angus (Trial X) and Beef Shorthorn steers had less fat over the 12th ribeye than short steers (2.0 and 1.5 mm, n.s., respectively). There was little difference in fat depth between Angus (Trial XI) and Hereford types (0.6 and 0.8 mm, n.s., respectively). When the depth of fat over the ribeye of the 12th rib was adjusted for right side weight short steers had a slightly greater depth of fat than rangy steers in Angus (2.5 mm, n.s.) and Beef Shorthorns (5.1 mm, n.s.) in Trial X. However in Trial XI rangy Angus steers had a slightly greater depth of fat than short steers (0.4 mm, n.s.), but there was no difference between types in Herefords. Rangy steers had larger ribeyes than short steers except in Herefords. The difference in ribeye areas between types was 2.51 cm2(n.s.) in Angus Trial X, 6.77 cm2(P<0.01) in Beef Shorthorns and 5.81 cm2(P<0.05) in Angus Trial XI. Short Hereford steers had larger ribeye areas than rangy steers by 3.77 cm2 (n.s.). These differences were reduced and became non-significant when adjusted for right side weight except in Herefords where short steers had significantly largerribeyes (6.76 cm2, P<0.01). Rangy steers had longer carcasses than short steers and longer bone measurements. They had a deeper carcass than short steers in Beef Shorthorn and Hereford steers, but not in Angus steers. The measurement of the depth of the carcass was influenced by fatness which appeared visually to increase the depth of short carcasses in relation to their skeletal size. The types did nof differ in the ratio of carcass length to carcass depth. When carcass dimensions were adjusted for right side weight the differences between types generally became non-significant except in Beef Shorthorn cattle. Rangy steers had slightly greater measures of carcass length, length of the leg and forearm, but had shorter measures of carcass depth than short-type steers except in Beef Shorthorns although the differences were not large. It was concluded that selection of rangy- compared to short-type weaner steers by visual assessment of conformation resulted in more beef being produced by the Angus, Hereford and Beef Shorthorn cattle. The reasons for increased production were various. In each comparison between types the superior initial weight of rangy weaner steers contributed about half of the increase in final yield of lean (assuming a similar composition at weaning). Rapid growth rate of rangy steers in Beef Shorthorn and Herefords contributed to their increased yield of lean although they were over-finished as a consequence of their greater growth rate and the experimental design requiring all cattle to be slaughtered at one time. Growth rate was not found to be an important factor in Angus steers where it appeared that a small superiority in carcass composition resulted in a greater yield of lean meat from rangy steers. Analysis of carcass composition and dimensions at slaughter showed considerable variation within each type. Ratios of body length to depth did not differ and in this respect rangy steers were "bigger" and heavier than short steers though not disproportionately so in relation to weight. The variation within each type suggested that some steers would have been classified into the other group had this been done at the conclusion of the trial. The ratio of body length to chest depth is not a true measure of skeletal size because of the influence of carcass fat in measuring chost depth. It would thus be unwise to draw conclusions about proportionality in size from this study. The experiment has indirectly shown the importance of a heavy weaning weight, of rapid growth rate, and of lean content in beef production. The relative importance of other factors such as age, pre-weaning growth rate, sire and dam and the pre-trial environment could not be assessed with the cattle purchased for this investigation. Visual assessment was not consistent in terms of selection for the same trait. This may have been due to the effect of different persons (between breeds) and their interpretation of "types" and to the amount of phenotypic variation for type in the population from which the steers were selected. The trends observed in this study are in the right direction to improve beef production of traditional beef breeds. The concept will be of use to farmers and others who choose cattle with or without records. The carcasses were graded either P1 or G in both trials. The number of carcasses in each grade were: Trial X G=33, P1=23; Trial XI G=16, P1=44, An analysis tested the hypothesis that there were no differences between grades in carcass characteristics. Carcasses graded G were heavier (15.4 kg, P<0.05) in Trial X, but not significantly so in Trial XI (7.9 kg, n.s.). They had no more kidney and channel fat (1.10 kg, n.s., Trial X and 0.56 kg, n.s. Trial XI) than carcasses graded P1. Results for other carcass characteristics were inconsistent between trials. Carcasses graded G in Trial X had a greater depth of fat over the 12th ribeye (2.4 mm, P<0.05), and a greater proportion of excess fat and less trimmed lean of the right side of the carcass (2.26% fat, P<0.001, and 1.58% lean, P<0.05). These results agree with grade expectations. In Trial XI however, carcasses graded G had the same fat depth over the 12th ribeye (0.0 mm, n.s.), less excess fat trim and more lean as a percentage of right side weight (1.74% fat, P<0.01, 1.72% lean, P<0.05) in direct contradiction to the results of Trial X and of grade expectations. Subjective visual assessment of fat depth from the uncut surface of the carcass resulted in 60 and 88 percent of carcasses being wrongly classified in relation to G grade standards (Trials X and XI, respectively). Graders had more success in classifying "leaner" carcasses 30 and 25 percent of carcasses graded P1 had fat depths outside the grade specification (Trials X and XI, respectively) and then by only a few millimetres. Carcasses graded G in Trial X were of a similar "size" to those graded P1, but were heavier, whereas in Trial XI carcasses graded G were "larger", but of a similar weight.Item Influence of plane of nutrition on the productivity of Angus heifers : a thesis presented in partial fulfilment of the requirements for the degree of Master of Agricultural Science in Animal Science at Massey University(Massey University, 1977) Anderson, Warren JamesThis experiment was designed to study the influence of autumn live weight and nutritionally-enforced live weight change on calf birth weight and the subsequent productivity of three-year-old, primiparous Angus heifers, calving in the spring of 1975. All heifers were pasture fed on "Tuapaka", No. 3 sheep farm, Massey University, and the treatments imposed followed those normally experienced by cattle on hill country. This was achieved by altering pasture intake by the manipulation of stocking rate during first pregnancy. The research herd of 54 heifers was comprised of animals reared to two-and-a-half-years-of-age at three different origins, namely Massey (Tuapaka), Hawke's Bay and Wairarapa, which consequently gave the three autumn live weight groups. On 1 May, 1975, a switchover design for pre-calving nutritional plane was initiated by allocating heifers within origin to one of three treatment groups. The first group of 19 heifers was fed at a high plane continuously to calving. A second group of 18 heifers was fed at a high plane of nutrition for 70 days (to 10 July, 1975) until three weeks before the start of calving (30 July, 1975). The third group of 17 heifers was fed on a low plane of nutrition from 1 May to 10 July, 1975, when it was switched to a high plane. The three groups were identified as HP-HP, HP-LP and LP-HP, respectively. The least squares means for the live weight of the groups at the start of the experiment, at switchover 70 days later, and at the last weighing date before calving were: 1 May, 1975: HP-HP, 382.4kg; HP-LP, 382.0kg; LP-HP, 380.1kg (NS). 10 July, 1975: HP-HP, 381.3kg; HP-LP, 382.1kg; LP-HP, 362.2kg (p<0.01). 25 July, 1975: HP-HP, 395.7kg; HP-LP, 376.0kg; LP-HP, 375.0kg (p<0.01). The live weight of the heifers, as classified by origin at the last weighing date before calving (25 July, 1975), did not differ from that at the start of the experiment (1 May, 1975) by more than 1.7kg. The least squares means for the weight of the heifers of the origin groups at 25 July was: Massey, 367.8kg; Hawke's Bay, 407.4kg; Wairarapa, 371.7kg, The Hawke's Bay heifers were significantly (p<0.01) heavier than those from the other two origins. The first order interaction between winter nutritional regime and autumn live weight was not significant. The birth weight of the calf was not significantly influenced by the plane of nutrition of the dam or her autumn starting weight. Within treatments, the least squares means for birth weight were: HP-HP, 27.8kg; HP-LP, 25.7kg; LP-HP, 25.9kg. The maximum difference was 2.1 kg. (0.05Item The onset of puberty and herbage intake in different selection lines of Angus cattle : a thesis presented in partial fulfilment of the requirements for the degree of Master of Appled Science (MApplSc) in Animal Science, Institute of Veterinary, Animal and Biomedical Sciences, Massey University, Palmerston North, New Zealand(Massey University, 2003) Martínez-Marecos, José MaríaThe onset of puberty and herbage intake in different selection lines of Angus cattle. MApplSc Thesis, Massey University, Palmerston North, New Zealand. 121 pp. Puberty onset and herbage dry matter intake was measured in four lines of Angus cattle selected for High and Low EBV-600 day weight (HG and LG respectively) and High and Low EBV-milk (HM and LM respectively). The heifers were generated on four industry farms in the North Island of New Zealand. Heifers from the HG line were younger at puberty (438.6 ± 9.3 days P < 0.01) than heifers from the HM (459.4 ± 7.1 days) and LM (476.1 ± 7.8 days) lines. No difference in age at puberty between HG and LG (455.1 ± 11.8 days) lines were found. Average weight at puberty across all genetic lines was (349.6 ± 9.9 kg). There was no difference among the four genotypes for this trait. Ninety-five percent of the animals reached puberty by the end of the trial and there was no difference in the percentage of animals reaching puberty by genetic line. Animals coming from Farms 1 and 3 tended to reach puberty earlier than animals coming from Farms 2 and 4. There was no differences in pregnancy rate among the genetic lines and the overall pregnancy rate was 90 %. Intake was measured on two occasions using n-alkanes (Ml and M2 respectively) and the pre- and post-grazing technique (M3 and M4 respectively). Average liveweight (LW) and estimated herbage intake at Ml was 240.2 ± 0.4 kg and 3.47 ±0.1 kg DM respectively. The values at M2 were 287.2 ± 1.9 kg LW and 6.50 ± 0.36 kg DM. No differences in estimated herbage intake among the genetic lines were detected in Ml or M2. In M3 heifers had an average LW of 247.1 ± 0.7 kg and mean estimated intakes of 4.86 ± 0.26; 4.17 ± 0.26; 4.37 ± 0.26 and 3.00 ± 0.26 kg DM for the HG, LG, HM and LM lines. The LM line having a significantly (P < 0.05) lower estimated intakes than the other lines. Average LW at M4 was 272.5 ± 0.6 kg. Animals from the LM (7.28 ± 0.19 kg DM) line had significantly (P < 0.05) higher intakes than animals from the LG (6.52 kg ± 0.18 DM) and HM (6.71 ± 0.18 kg DM) lines. Intakes from the HG (6.99 ± 0.18 kg DM) animals was not significantly different from intakes of the other genetic lines. In general the HG heifers outperformed the heifers from the other lines in puberty onset and feed conversion efficiency. However, in a self-replacing beef cowherd, the higher maintenance cost and lower milk production of dams from the HG line should be considered. Combining the growth characteristics of the HG lines with an appropriate level of milk production into a selection index would produce animals with the adequate combination of genes for a self-replacing beef cowherd.Item The wintering and calving of Angus beef cows on a sawdust pad : a thesis presented in partial fulfilment of the requirements for the degree of Master of Agricultural Science in Animal Science at Massey University(Massey University, 1974) Pleasants, Anthony BryanA system of wintering and calving beef cows on a sawdust cattle pad was compared with the traditional method of wintering unsupplemented cows on hill country pasture. Comparisons were made over four years, beginning in 1970. Two herds of Angus beef cows were used in the experiment. One herd was originally the Massey University Stud herd, which included approximately 50 cows aged from three to ten. Three-year-old replacements were added to this herd each year. This herd was designated the Stud herd. The other herd designated the Commercial herd, was based on 67 yearling heifers bought in 1969. These cows were all of the same age, and no replacements were added. In 1969 25 cows from this herd were mated to calve at two-years-of-age. The two herds were run together as one unit during the trial, distinction only being made for the purpose of statistical analysis. The pad consists of two yards with sawdust packed on top of tile drains. A concrete apron runs along the side where the feeding racks are situated. A stand of pampas grass protects the pad from the prevailing wind. Half gates were installed, and the bottom rails of the yard were removed to allow the calves to get out and creep feed on the adjoining pasture. Three weeks before calving begins cows were allotted to the pad or the hill treatment using a table of random numbers. In 1971, 1972, 1973 a switchover design was adopted, whereby some animals alternated between the two treatments in successive years, while others wintered on the same treatments. Over 1970 the cows were confined all the time. In 1971 the cows on pad I were allowed to break feed saved pasture over a week. In 1972 and 1973 the cows and calves were removed from the pad for three and four days after birth respectively. This enabled the calf to obtain colostrum without interference, allowed the cow to build up reserves of vitamin A, helped form a bond between the calf and its mother, and enabled the calf to have the benefit of a healthier environment for the first days of its life. This practice appeared to have some merit in reducing the incidence of calf scours. While confined the cows were fed hay, barley straw, and barley meal. In 1970 some experimentation in feeding levels was necessary, and in 1971, 1972 and 1973, 4.3 kg hay, 2.3 kg barley straw and 0.6 kg of barley meal per head per day were fed. In 1972 and 1973 feeding once a day was compared with feeding the same ration once every second day. Before the cows were confined, the top three inches of sawdust was removed and the sawdust and timberwork sprayed with a 10% solution Of formalin. In 1973 the concrete apron was scraped off weekly with a tractor and blade. Milk determinations were made by the weigh-nurse-weigh method following a 16 hour separation. The cows entered the pad about the second week in July, and remained there until the end of September, when they joined their contemporaries on the hill. Generally the cows wintered on the pad lost more weight than the cows grazed on the hill, although the magnitude of the weight lost varied considerably between years. Birth weights of the calves born on the pad were generally about 2 kg below that of the calves born on the hill. However, there were no clear differences between treatments for the weaning weights. Limited information gathered on the cow milk production indicated that although milk weights of the cows on the pad were lower during confinement, handicapping the growth of their calves, there appeared to be a surge of milk production in these animals upon their release to the hill pasture, in some years. This resulted in an increased growth rate of the calves from the pad at this time. Reproductive performance of the three-year-old and mature cows as measured by thoir calving interval was unaffected by the winter treatments. The performance of the first calving two-year-old heifers from the Commercial herd in 1970 was adversely affected by the pad treatment. Birth weights and weaning weights were reduced and 26.5% of the heifers failed to rebreed the following season. Nevertheless subsequent performance demonstrated no further effect of calving at two-years-of-age under adverse conditions. There was no effect on the calf performance of feeding everyday against feeding every second day. Neither was calf performance affected by any of the switching treatments imposed between years. Differences due to the effect of sex and age of dam were similar to those reported in the literature for birth weight and weaning weight. As the four-year-old dams performed surprisingly well in this study an age-of-dam x treatment interaction was suspected. There was an indeterminate effect of sex on the milk yield of the dam. Regressions involving the age of the calf on the weight at various points revealed a strong association of growth with climatic variables. Since the period under study included stormy weather and long droughts this complicated the evaluation of calf growth data. It was concluded that the pad system of wintering and calving beef cows can be operated as a commercial system in the manner described. A discussion of pad husbandry is given, and recommendations are made.Item A study of adjustment factors for the weaning weights of Hereford and Angus calves : a thesis presented in partial fulfilment of the requirements for the degree of Master of Agricultural Science in Animal Science at Massey University(Massey University, 1975) Nicoll, Geoffrey BlairFrom the files of the Beef Cattle Weight Gain Performance Recording Scheme of the New Zealand Meat Producers Board and the New Zealand Wool Board, the weaning weights of 7771 Hereford calves born in 18 herds, and 16666 Angus calves born in 37 herds, from 1964 to 1972, were analysed. Objectives of the study involved estimation of the effects of age and sex of calf, and age of dam, in order that methods of adjustment currently used in the National Beef Recording Service for these environmental influences could be evaluated. Each calf was classified according to herd, year of birth, age-of-dam group, and sex, with age at weaning as a covariate. The data were analysed within breeds by least squares to investigate the main effects of these five factors and the first-order interactions among herd, year, age-of-dam group, and sex effects. The importance of each interaction was examined by comparing the proportionate reduction in intra-class residual variation after all main effects had been fitted. The results of the analyses of main effects indicated that for each breed, all effects contributed to more than a 2 percent reduction in intra-class residual variance. The results of the interaction analyses showed that only the herd x year interaction for Hereford calves, and the herd x year and herd x sex interactions for Angus calves, contributed to at least a 2 percent reduction in residual variance after all main effects had been fitted. Within-subclass linear regression coefficients of weight on age at weaning for Hereford and Angus calves, were 0.70 ± 0.01 and 0.62 ± 0.01 kg/day, respectively. Least-squares estimates for sex indicated that the weaning weights of Hereford and Angus males were heavier than those of females by 29.8 and 25.6 kg, respectively. Estimates for age of dam indicated that the weights of Hereford calves out of dams of 2, 3, 4, 5 and, 10 years of age and older, deviated from the weights of Hereford calves out of mature dams (6 to 9 years-old) by 33.3, 17.6, 8.7, 3.8 and 2.2 kg, respectively. The corresponding deviations for Angus calves were 22.7, 15.2, 7.9, 5.4 and 1.4 kg. Estimates for age-of-dam effects were also obtained by best linear unbiased estimation procedures from the records of 7698 Hereford calves out of 2901 dams, and 14198 Angus calves out of 5086 dams. Differences in the estimates of deviations of non-mature from mature dam age groups derived by least squares and by best linear unbiased estimation, were in general relatively small. In relation to the procedure currently used in the National Beef Recording Service, alternative adjustment procedures derived for age at weaning involved additive and multiplicative applications of linear regression of weight on age for each breed. The current procedure, for both breeds, was the least effective in reducing the dependence of adjusted weight on age, whilst the procedure additively applying linear regression of weight on age was the least effective in reducing intra-class residual variance. Adjustments determined for age-of-dam effects by least squares and by best linear unbiased estimation, were considered to differ only slightly from current industry adjustment factors, with the exception of factors applicable to Angus calves out of 3-year-old dams. Examination of the variances within age-of-dam groups, and of the reductions in residual variances within herd-year-sex subclasses, indicated the applicability of additive, rather than multiplicative, adjustment factors for each breed. Comparisons of additive and multiplicative adjustment factors for sex effects were varied. Multiplicative adjustments were more appropriate in equalizing variances within sex groups, whilst additive adjustments were more appropriate in reducing residual variance within herd-year subclasses.Item Inbreeding and population structure studies in the New Zealand Angus breed : a thesis presented in partial fulfilment of the requirements for the degree of Master of Agricultural Science in Animal Science at Massey University(Massey University, 1977) Cheong, Weng KeongThe breed structure and genetic history of the New Zealand pedigree Angus breed were analysed by Robertson and Asker's (1951) modification of the Wright-McPhee (1925) pedigree sampling method. The pattern of the breed structure obtained is generally similar to that found in other studies, but it is both diffuse and dynamic owing to the present rapid expansion of the breed. There are changes taking place in the herd composition of the major breeders' herds and many new herds have yet to find their level in the structure. Considerable emphasis has been placed on the use of imported animals in the development of the breed. Of all herds registering in Volume 61 of the herd book, 20.5% used imported sires, and the percentage of genes in the breed in 1966/67 derived from animals imported since 1863 was 85.4. The most important herd in 1969 has a genetic contribution to the breed of 21.9 per cent:, while the contributions of the four next most important herds were 8.72, 8.7, 4.7 and 3.7 per cent. In the four-generation pedigrees from which these figures were derived, the contribution of imported animals was 42.4%. The relationship between herd size and importance of the herd was considered. Herd duration was also discussed, in so far as it relates to improvement of the breed. The animal with the highest relationship to the breed was Blackleg (11.65% in the 1900 pedigree sample). But overall, the most important animal over the period 1900-1966/67 was Lancer of Advie. Of the 33 sires and 9 dams whose direct relationships are 3.0% or more in any of the 8 sample years, 19 sires and 3 dams were imported. The total inbreeding in 1966/67 (base year 1863) was 1.80%. This comprised 0.09% current inbreeding, 0.95% long-term inbreeding, and 0.76% strain inbreeding. The index of subdivision calculated from the non-current and long-term inbreeding is 1.79, indicating that there is only a slight tendency towards family formation in the breed. The effective generation length is approximately 5.6 years. About 50-56% of the animals in the 1966/67 sample were sired by bulls 4 years old or younger, while about 38% are from dams 4 years or younger. It is unlikely that there is much genetic variation between herds. This is because bulls from major breeders' herds are used widely throughout the breed while about 80 percent of sires and 37 per cent of dams are bred in herds other than the one in which they were used.Item Prediction of milk yield of 3-year-old Angus cows and the influence of maternal milk production on the postnatal growth of beef steers : a thesis presented in fulfilment of the requirements for the degree, Master of Sicnece (Animal Science), Massey University, Palmerston North, New Zealand(Massey University, 2013) Roca Fraga, Fernando JavierMaternal milk production influences calf weaning weight which is the major driver for economic return in a cow-calf operation. The objective of this study was to use measures of calf milk intake to estimate milk production of Angus (AA; n=43), Angus×Friesian (AF; n=32), Angus×Jersey (AJ; n=40) and Angus×Kiwi-Cross (AK; n=21) cows, and to determine how milk yield was related to calf growth rate (n=64) from birth to one year of age. Milk production was estimated by the weigh-suckle-weigh (WSW) technique at an average 32, 49, 80, 120 and 160 days (D) post-partum. Third-order Legendre polynomials were fitted to milk data using random regression to estimate the lactation curve for each cow. Live weight of all steers was recorded at birth and thereafter accompanying every WSW measurement. Postweaning live weight was recorded at an average D240, D330 and D350 of age. Growth curves for each steer were estimated by fitting third-order Legendre polynomials to live weight data using random regression. The average total milk production from D32 to D160 was 1337 ± 22 kg for AF cows, 1245 ± 20 kg for AJ cows, 1301 ± 32 kg for AK cows and 1017 ± 20 kg for Angus cows. The AF, AJ and AK cows produced more (P<0.05) milk from D32 to D160 than the AA cows. The AF cows produced more (P<0.05) milk than AJ cows, with AK cows being intermediate and not differing (P>0.05) from either AF or AJ cows. Crossbred cows produced more milk (P<0.05) at all stages of lactation when compared with straightbred AA cows. In the present study, as the proportion of Friesian or Jersey in the crossbreds increased from 0 to 50%, an extra 325 kg and 240 kg of milk, respectively, was expected compared to the AA cows. Total energy intake from milk was higher (P<0.05) for the AF-, AJ- and AK-reared steers compared to those reared by AA dams. This resulted in higher liveweight gains so that steers reared by crossbred cows were heavier (P<0.05) from D60 to D270 than those reared by AA cows. Results also revealed that the higher live weight at D60 in AJ-reared steers compared to AA-reared steers was due to differences in milk consumption from D32 to D60. The higher live weight of AF- and AK-reared steers at D60 compared to AA-reared steers was attributed to a maternal effect on steer size; however, from D90 until weaning at D160, any differences in live weight were due to differences in milk consumption. Estimation of the theoretical pasture consumption revealed that AA- reared steers compensated for the lower milk intake by eating more grass, however, this was not enough to support high daily gains during the pre-weaning period. The differences in live weight seen at weaning between steers were maintained post-weaning until D270 and were attributed to differences in milk consumption during the pre-weaning period. Under nonlimiting nutrient availability, AF, AJ and AK cows were able to prItem Assistance at parturition of primiparous, two-year-old, Angus heifers and the effect of liveweight gain of heifers in early pregnancy on birth weight of the calf : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Animal Science at Massey University, Palmerston North, New Zealand(Massey University, 2009) Hickson, Rebecca EdithA simulation showed that calving heifers for the first time at two compared with three years of age increased profitability of a beef breeding herd; however, profitability of calving two-year-old heifers was dependent on the incidence of assistance at parturition. The predominant cause of dystocia (and hence assistance at parturition) in beef breeding heifers is feto-maternal disproportion. This condition could be alleviated by reducing birth weight of calves relative to live weight of heifers. In a survey of farmers, 20% of those currently calving heifers at three years of age indicated that if the need for assistance at parturition was eliminated, they would calve their heifers at two years of age. In two surveys conducted of the same farmers in consecutive years, mean incidence of assistance at parturition in primiparous, two-year-old heifers was 7.0% and 9.5%, and reached 100% in some herds. Mortality rate by four weeks postpartum was 30% for assisted calves and 11% for assisted heifers. Methods of reducing the need for assistance at parturition in primiparous, two-year-old, beef breeding heifers would be of value to the beef cattle industry in New Zealand. The objective of this research was to identify whether manipulation of liveweight gain of primiparous, two-year-old, Angus heifers in the first trimester of pregnancy could be used to regulate birth weight of calves, and to identify factors contributing to the need for assistance at parturition. Three experiments were conducted in which heifers were fed for various rates of liveweight gain: 1. moderate versus low for the first trimester of pregnancy; 2. a 2 x 2 factorial experiment in which liveweight gain was 1220 high versus moderate for ten days prior to insemination, and moderate versus a loss for the first trimester of pregnancy; 3. high and moderate, moderate and a loss, or moderate and moderate for days 0-42 and 42-90 of pregnancy, respectively. Birth weight of calves was not affected by treatment in experiments 1 and 3. In experiment 2, birth weight of the calf relative to live weight of the heifer was least in the high-then-low treatment, but subsequent live weight of those calves was also less, partially negating any potential benefits to production. An additional experiment revealed similar fetal weight at the end of the first trimester for heifers that had moderate or low liveweight gain from 21 days prior to conception. Probability of assistance at parturition increased with birth weight of the calf and decreased with increased live weight of the heifer. Body dimensions of calves did not affect the likelihood of assistance. Assistance had no effect on subsequent performance of surviving animals. Manipulation of liveweight gain of heifers in the first trimester of pregnancy did not offer a means of reliably regulating birth weight of calves; however, the impact of assistance at calving did not justify delaying first calving until three years of age. Birth weight and assistance at calving can currently be best managed through selection of appropriate service sires for primiparous heifers.Item Studies on bovine mannosidosis : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Veterinary Pathology at Massey University(Massey University, 1976) Thompson, Keith GordonBovine mannosidosis is an inborn lysosomal disease of Angus cattle, associated with a deficiency of acidic α-mannosidase and a consequent disorder in the lysosomal catabolism of glycoproteins. Affected calves characteristically show signs of neurological derangement and usually die within their first year of life. The enzymic defect causes abnormal storage of water-soluble oligosaccharide units within membrane-bound vacuoles in various cell-types. Vacuolation is particularly severe in neurones of the central nervous system, reticuloendothelial cells of lymph nodes and liver, and exocrine epithelial cells of the pancreas, salivary glands and lacrimal glands. Certain cell-types of mesenchymal origin, including fibroblasts, mesangial cells, smooth muscle fibres, pericytes and capillary endothelial cells are also affected. There is evidence that the process of crinophagy may be important in contributing glycoprotein substrates to the lysosomal system, at least in the exocrine pancreas, while in some tissues vacuoles appear to develop as dilatations of Golgi apparatus or smooth endoplasmic reticulum. The more usual picture however was that of storage within vacuoles consistent with the structure of enlarged secondary lysosomes. Mannosidosis is inherited as a simple autosomal recessive disease and whereas acidic α-mannosidase activity is almost completely absent from the tissues and body fluids of affected homozygotes, heterozygous individuals possess a partial deficiency of the enzyme. This gene dosage relationship forms the basis of methods for differentiating heterozygotes from normal animals. A test based on plasma α-mannosidase activity has been evaluated on over 5,000 Angus cattle, and the prevalence of heterozygotes was found to be approximately 10%. Although plasma α-mannosidase activity has been shown to vary between cattle of different age and sex, and significant seasonal, between-herd and even between-mob differences were demonstrated, the teat is suitable for routine use in the control of mannosidosis on a herd basis. A more sophisticated test for mannosidosis heterozygotes, based on α-mannosidase activity in lymphocyte extracts has been developed and evaluated, and is a useful adjunct to the plasma test. Preliminary investigation of a further test, based on enzyme activity in granulocyte extracts, has produced encouraging results. Included in this thesis is an evaluation of an "experiment of nature" in enzyme replacement therapy, in which a chimeric mannosidosis calf had been endowed with a transplant of lymphocytes from a normal co-twin, due to fused placental blood circulations. This lymphocyte transplant reduced the severity of lesions in the liver, lymph nodes, pancreas and lacrimal glands of the chimeric calf but the vacuolation of neurones in its brain was of the same order of severity as that seen in positive control calves with mannosidosis, and the clinical course of the disease had not been significantly altered. It is concluded that enzyme replacement therapy by infusion of leucocyte suspensions is likely to be most effective in inborn lysosomal diseases with minimal neurological involvement.