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    Blood metabolite and hormone concentrations of dairy calves differing in genetic potential for milk fat production : a thesis presented in partial fulfilment of the requirements for the degree of Masterate of Agricultural Science in Animal Science at Massey University
    (Massey University, 1985) Xing, Guo Qiang
    The present study was conducted at the Massey University Dairy Research Unit to investigate the effect of genetic merit for milk fat production on the physiology and metabolism of Friesian calves. Twenty four Friesian calves divided into four groups namely High Breeding Index (HBI) heifers, HBI bulls, Low Breeding Index (LBI) heifers, and LBI bulls were challenged with four different experimental treatments, ie. fasting, feeding, intravenous arginine infusion, and subcutaneous synthetic corticosteroid injection at ten to eighteen days of age. A total of eighteen blood samples were collected from each calf through an indwelling jugular cannula and the concentrations of plasma glucose, insulin, GH and cortisol were determined. Some statistically significant differences were found in plasma metabolite and hormone concentrations between the HBI and LBI groups. 1. The basal glucose concentration in HBI group was significantly higher than that in LBI group (P<0.05). The basal plasma insulin concentration was also significantly higher in HBI group than in LBI group (P<0.01). The basal GH concentration in HBI calves was higher in HBI calves than in LBI calves, but the difference was not quite significance at 5% level (P=0.059). 2. Following feeding, plasma insulin and GH concentrations in HBI group were significantly higher than those in LBI group (P<0.01, P<0.05 respectively). 3. Acute intravenous arginine infusion induced hyperinsulinemia and hypoglycemia in all calves. LBI calves had significantly higher increments of plasma insulin measured as a percentage of basal levels than HBI calves. The response of GH concentration to arginine challenge differed significantly in terms of level and pattern between HBI and LBI groups, with the HBI calves having more prolonged higher GH concentration than LBI calves (P<0.05). 4. Subcutaneous injection of synthetic corticosteroid resulted in significant increments in plasma glucose and insulin concentrations, and a significant decrease in endogenous cortisol production in all calves. (P<0.01, P=0.05, P<0.01 respectively). But no significant differences were detected between HBI and LBI groups. Effects of sex on plasma metabolite and hormone concentrations were also found in the present study. Plasma insulin concentration was consistantly higher in bulls than in heifers and the differences were significant at the time of fasting, after feeding, and after arginine infusion (P<0.01). Plasma glucose concentrations following feeding were significantly higher in bulls than in heifers (P<0.05). GH concentration was slightly but not significantly higher in bulls than in heifers for most of the experiment. It was concluded that differences exist in some important metabolic and endocrinological characteristics between HBI and LBI calves, and these differences could become significant under certain physiological conditions and experimental treatments such as those applied in the present study. This study also showed the promise of identifying genetically superior Friesian dairy cattle at an early age by using physiological markers. However this possibility has yet to be tested by earring out measurements on calves for which breeding index value for milk fat production will be determined by methods such as progeny test.
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    A study of aspects of utilization of tallow by young milk-fed calves : a thesis submitted in partial fulfilment of the requirements for the degree of Master of Agricultural Science at Massey University
    (Massey University, 1973) Betteridge, Keith
    1. Three groups of 4 Friesian bull calves were individually fed from 7 days of age on one of the following diets; (L) - Butter-milk powder (B.M.P.) to promote 0.45 kg liveweight gain (LWG)/day; (H) - B.M.P. to promote 0.67 kg LWG/day; (HT) - B.M.P. supplemented with beef tallow to promote 0.67 kg LWG/day. The diets, reconstituted to 15% dry matter (d.m.), were fed. in direct proportion to the animal's liveweight at the beginning of each of the 3 consecutive 10-day experimental periods. N.B. Skim milk powder (S.M.P.), initially used as the basal diet, was subsequently replaced, by B.M.P. and the trial was restarted. 2. Daily faecal d.m. consistency was subjectively scored on a 0 - 5 sca1e. Quantitative measurements were made in conjunction with the faecal collections for the nitrogen balance. 3. Nitrogen balance data were collected from of the 4 calves, in each group during the last 5 days, and energy balance data during the last 2 days of each period. 4. The addition of 4% tallow (d.m. basis) significantly reduced the incidence of scours (p<0.01) in calves fed a basal diet of either S.M.P. or B.M.P. 5. Mean LWG's of calves on treatments L, H and- HT were respectively 0.57, 0.73 ard 0.62 kg/day; these differences were not statistica1ly significant (p > 0.1). 6. The calves on treatment H, although having the highest urinary nitrogen excretion (p < 0.05), retained the most nitrogen (g/kg 0.75/day) (p < 0.05). The ratio of digested nitrogen retained : M.E. intake was highest for the calves fed the tallow supplement. This suggests that energy rather than protein is the factor most limiting protein deposition in calves fed solely on B.M.P. 7. During the second and third periods diets H and HT promoted a significantly greater retention of energy than did diet L (p < 0.01). The percentage of energy retained as fat tended to be higher in calves on treatment H. 8. The maintenance enerey requirement for a 50 kg calf was estimated to be 53.5 kcals D.E./kg liveweight. The efficiency of utilisation of M.E. for growth was found to be 78%.
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    The energy metabolism of young Friesian calves fed on a diet consisting of milk and meal : a thesis presented in partial fulfilment of the requirements for the degree of Master of Agricultural Science at Massey University, New Zealand
    (Massey University, 1977) Hughes, Terence P.
    Two Friesian bull calves were selected from those born each week for six weeks during March and April 1975. The twelve calves were used in an experiment to study the energy metabolism of young calves when fed a milk and meal diet. 1. All calves were reared on fresh whole milk with pelleted concentrate available ad lib. Between 21 and 42 days of age intake was adjusted so that each animal received half of its daily allowance of ME from milk and half from meal. From each pair, one calf was assigned randomly to a high level, and its pair mate consequently to a low level of feeding. 2. Energy and nitrogen balances (seven days duration) were measured once for all pairs of calves and twice for the last three pairs. 3. Heat production (MJ/day) was related to liveweight (kg) by HP = .200 LW.980, and metabolizable energy to liveweight by ME = .340 LW.922. 4. The data for heat production, metabolizable energy intake and energy retention were interpreted to provide estimates of 'true' net energy required for maintenance of 0.26 MJ/kg0.75 daily. 5. The pooled values for ME required for maintenance were 0.37 and 0.41 MJ ME/kg0.75 daily determined by simple and multiple regression techniques respectively. The net efficiency of utilization of ME above maintenance was 0.63 determined by simple regression. 6. Pooled values for the partial net efficiencies of utilization of ME for the synthesis of protein and fat were 0.38 and 1.00 respectively. 7. ME required above maintenance per kg of liveweight gain was 16.53 and 12.85 for the high and low feeding levels respectively. The difference between these values was not significant and the pooled value was 14.89 MJ ME/kg liveweight gain. 8. Methane losses accounted for less than 2% of GE. The metabolizability (ME/GE) of the combined diet was 78% and DE/ME 0.94. 9. Obligatory losses of N were 0.19 gN/d/kg0.75, N maintenance (Nm) was 0.35 gN/kg0.75 daily, the digestibility was 81% and the biological value 0.53.
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    The effect of milk feeding levels on growth rates of high and low BI Friesian bull calves before and after weaning : a thesis presented in partial fulfilment of the requirements for the degree of Master of Agricultural Science at Massey University, New Zealand
    (Massey University, 1984) Wang, Xinjun
    Eight Friesian bull calves from high breeding index parents (HBI, BI of parents = 134) and eight from low breeding index parents (LBI, BI of parents = 103) were used to estimate the effects of milk intake and BI on calf growth performance, voluntary herbage intake, digestion and nitrogen metabolism. 1. The calves were allocated to one of two levels of milk intake from 3 weeks of age until weaning at about 7.5 weeks of age. The milk was fed twice daily at either 4.5 (LM) or 6.0 (HM) litres/calf/d. 2. Daily intakes of freshly harvested herbage (perennial ryegrass and white clover pasture) offered ad libitum throughout the pre-weaning period and for a further 3 weeks period following weaning, were measured. 3. The calves were then grazed on pasture together in a mob and the liveweight at 21-25 weeks of age was measured. 4. Calf growth rates at various stages were recorded. The HM calves grew significantly (p<0.05) faster than LM calves (0.55 v 0.44 Kg/d) in the pre-weaning period. Their growth rate was slower in the 3 weeks following weaning (0.21 v 0.31 Kg/d) but the difference in this period was not significant. 5. The overall growth rate from 3 to 21-25 weeks of age was not significantly different between HM and LM calves (0.52 v 0.53 Kg/d), nor was the calf LW at 21-25 weeks of age (124 v 130 Kg for HM and LM calves respectively). 6. LM calves consumed significantly (p<0.01) more herbage organic matter (OM) both before and after weaning (0.18 and 0.33 Kg OM/d pre-weaning and 1.13 and 1.28 Kg OM/d post-weaning for HM and LM calves respectively). Reducing daily milk intake by 1 Kg increased daily herbage OM intake by 0.11 Kg before weaning and by 0.12 Kg after weaning. The difference in herbage intake caused by milk intake level persisted for two weeks following weaning. It was not significantly different in the third week after weaning. 7. It was demonstrated that the LW at the commencement of the experiment (3 weeks of age) was positively correlated with the mean overall growth rate (from 3 to 21-25 weeks). LW at 3 weeks of age was also positively correlated with the voluntary herbage intake in the third week following weaning, and also digestibility of herbage organic matter in the post-weaning period. 8. By extrapolating the linear relationship between nitrogen retention (NR) and nitrogen intake (NI) per metabolic weight (Kg0°75 ), the estimated nitrogen requirement for maintenance (Nm) was 0.418 g N/Kg0°75/d. 9. There were no significant differences in growth rate, herbage voluntary intake, digestibility or nitrogen metabolism between the BI groups, nor any interactions between the BI and levels of milk intake.