Browsing by Author "Stafford KJ"
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- ItemCondition-dependent maternal sex allocation in horses can be demonstrated using a biologically relevant, multivariable condition measurement(John Wiley and Sons, Inc., 2024-02-01) Chin YY; Rogers CW; Gee EK; Stafford KJ; Cameron EZ; Nichols H; MacLeod K; Palmer MMaternal condition is influenced by multiple variables that individuals experience at seasonal and local levels, and thus condition-dependent sex allocation is likely also multifactorial. Here, we test the Trivers-Willard Hypothesis (TWH) using a multivariable approach on a dataset of thoroughbred mare breeding records. There is no sex ratio variation when examined at univariable level, mirroring the usual approach to test condition-dependent sex allocation. Conversely, the multivariate model shows multiple variables interact to influence the likelihood of producing a male. Mare and management variables that represent better body condition is associated with an increase in likelihood of a male offspring. The magnitude and direction of sex ratio skew correspond closely with predicted mare energy balance, consistent with TWH predictions. Our findings therefore support the TWH and show that, while sex allocation is multifactorial, maternal energy status emerges as the dominant driver. The additive and agonistic interactions of different variables demonstrate that a multifactorial approach should be a key consideration in sex allocation studies.
- ItemDoes ewe nutrition during pregnancy affect the neonatal behaviour of twin-born lambs?(2016) Gronqvist GV; Hickson RE; Corner-Thomas RA; Kenyon PR; Stafford KJ; Morris STIn this experiment the effects of feeding treatments from mid pregnancy until lambing on the behaviour of twin-bearing ewes and their lambs were investigated. Fifty seven four-year-old Romney ewes were offered a medium (1164 ± 31.6 and 819 ± 16.0 kg DM/ ha pre- and post-grazing pasture mass, respectively) or ad libitum (2181 ± 47.6 and 1431 ± 24.6 kg DM/ha pre- and post-grazing pasture mass, respectively) feeding treatment from day 76 of pregnancy until after lambing. At ear-tagging the time taken for the lambs to stand, make contact with, suck from and follow their dam was recorded. A maternal behaviour score based on the distance the ewe moved away from her lambs during tagging was also recorded. Survival analysis showed that lambs born to ewes offered the medium feeding treatment from mid pregnancy until lambing were quicker to stand, suck and follow compared with lambs born to ewes offered the ad libitum feeding treatment (P<0.05). It is unclear whether these behaviours indicate that lambs born to ewes in the medium treatment were more vigorous or that they had unmet needs that prompted the apparent increase in vigour. Ewe feeding treatments did not affect the maternal behaviour of the ewes.
- ItemEvaluating the long-term conformation and hoof growth effects of starting hoof trimming at 5 months of age in New Zealand dairy goats(Federation of Animal Science Societies and Elsevier Inc on behalf of the American Dairy Science Association, 2023-02) Deeming LE; Beausoleil NJ; Stafford KJ; Webster JR; Cox N; Zobel GHoof overgrowth is associated with poor conformation, an altered weight-bearing surface, and a reduction in the hoof's anatomic and functional integrity. As a result of housing systems that promote hoof overgrowth, hoof trimming is considered a priority in dairy goats. However, there are few data on the effects of the timing of first trimming on hoof conformation and growth rate. The aims of this study were (1) to evaluate the long-term effects of 2 different hoof trimming start times and (2) to investigate the pattern of hoof growth across the first 2 yr of life. Eighty 5-mo-old female Saanen-cross commercially housed dairy goats were allocated randomly to 1 of 2 treatments: (1) early trimmed (trimming beginning at 5 mo old; hooves were trimmed every 4 mo thereafter) and (2) late trimmed (trimming beginning at 13 mo old; hooves were trimmed every 4 mo thereafter). Using a combination of photographs and radiographs, hoof conformation, joint positions, and hoof wall length were assessed before the 13- and 25-mo trimming events. Hoof growth was assessed every 12 wk using caliper measurements. Overall, starting hoof trimming earlier had minor and inconsistent effects. However, detrimental changes in conformation and joint positions occurred between trimming events, particularly in the hind hooves, regardless of trimming treatment. At both assessments, there was a high percentage of overgrown toes and dipped heels, with the hind hooves being more affected compared with the front (overgrown toes at 13 mo, 97.1 vs. 79.1 ± 5.2%; overgrown toes at 25 mo, 91.7 vs. 56.3 ± 6.7%; dipped heels at 13 mo, 98.5 vs. 19.3 ± 5.0%; dipped heels at 25 mo, 88.3 vs. 4.9 ± 4.8%). In addition, at both assessments, the distal interphalangeal joint angle was greater in the hind hooves compared with the front (13 mo, 79.5 vs. 65.2 ± 1.7°; 25 mo, 79.0 vs. 66.7 ± 0.9°), whereas heel angles were less in the hind hooves compared with the front (13 mo, 41.8 vs. 57.1 ± 1.5°; 25 mo, 44.9 vs. 55.9 ± 1.1°). On average, the front hooves grew 4.39 mm/mo and the hind hooves grew 4.20 mm/mo. Early trimming did not have consistent effects on hoof growth rate. Importantly, our results suggest that trimming every 4 mo is not sufficient to prevent hoof overgrowth, the development of poor conformation, and detrimental changes in joint positions, particularly in the hind hooves. Furthermore, the detrimental changes may have masked any long-term treatment effects. Therefore, trimming frequency and age of first trimming should be considered when devising hoof care protocols for dairy goats housed in environments that do not offer opportunities for natural hoof wear.
- ItemHeart Rate and Heart Rate Variability Change with Sleep Stage in Dairy Cows(MDPI (Basel, Switzerland), 2021-07-14) Hunter LB; Haskell MJ; Langford FM; O'Connor C; Webster JR; Stafford KJ; Van Eerdenburg FJCMChanges to the amount and patterns of sleep stages could be a useful tool to assess the effects of stress or changes to the environment in animal welfare research. However, the gold standard method, polysomnography PSG, is difficult to use with large animals such as dairy cows. Heart rate (HR) and heart rate variability (HRV) can be used to predict sleep stages in humans and could be useful as an easier method to identify sleep stages in cows. We compared the mean HR and HRV and lying posture of dairy cows at pasture and when housed, with sleep stages identified through PSG. HR and HRV were higher when cows were moving their heads or when lying flat on their side. Overall, mean HR decreased with depth of sleep. There was more variability in time between successive heart beats during REM sleep, and more variability in time between heart beats when cows were awake and in REM sleep. These shifts in HR measures between sleep stages followed similar patterns despite differences in mean HR between the groups. Our results show that HR and HRV measures could be a promising alternative method to PSG for assessing sleep in dairy cows.
- ItemRisk-Factors for Soft-Tissue Injuries, Lacerations and Fractures During Racing in Greyhounds in New Zealand(Frontiers Media S.A., 2021-12-03) Palmer AL; Rogers CW; Stafford KJ; Gal A; Bolwell CF; Bruyette DRecognition of injuries in racing animals is essential to identify potential risk factors so actions can be taken to reduce or mitigate the cause of the injury to safeguard the animal. Racing greyhounds are subject to musculoskeletal injuries associated with athletic pursuit, in particular soft-tissue injuries, lacerations, and fractures. The objective of this study was therefore to determine risk factors for soft-tissue injuries, lacerations and fractures occurring during racing, using a cohort of greyhounds racing in New Zealand between 10th September 2014 and 31st July 2020. Dog-level, race-level and track-level risk factors for each outcome were assessed using mixed-effects multivariable logistic regression including trainer as a random effect. Throughout the study period there were 218,700 race starts by 4,914 greyhounds, with a total of 4,385 injuries. Of these, 3,067 (69.94%) were classed as soft-tissue injuries, 641 (14.62%) were reported as lacerations, and 458 (10.44%) were fractures. Greyhounds with a low racing frequency (racing more than 7 days apart) had 1.33 [95% confidence interval (CI): 1.06-1.67] times the odds of fracture compared to those racing more frequently. Older greyhounds had a greater odds of fracture compared with younger greyhounds. Racing every 7 days had a lower odds of soft-tissue injury compared with racing more than once a week. Dogs over 39 months had 1.53 (95% CI: 1.35-1.73) times the odds of sustaining a soft-tissue injury compared to the younger dogs. Greyhounds originating from Australia had a higher odds of fracture and laceration compared with New Zealand dogs. Better performing dogs (higher class) had a greater odds of fracture and laceration whilst maiden dogs had a higher odds of soft-tissue injury. Greyhounds starting from the outside box had a higher odds of fracture. There was considerable variation in the odds of soft-tissue injury at different racetracks. In conclusion, although the incidence of soft-tissue injuries was higher than other injury types, the repercussion of such injuries was less than those for fractures. The results from this study will help to inform intervention strategies aimed at reducing the rate of injuries in racing greyhounds, enhancing racing safety and greyhound welfare.
- ItemThe effect of nutrition and body condition of triplet-bearing ewes during late pregnancy on the behaviour of ewes and lambs(Asian-Australasian Journal of Animal Sciences, 2018-12) Gronqvist GV; Corner-Thomas RA; Kenyon PR; Stafford KJ; Morris ST; Hickson REOBJECTIVE: Triplet-born lambs are less likely to survive to weaning than twin-born or single-born lambs. Appropriate ewe-lamb bonding behaviours and lamb vigour behaviours are necessary for survival of lambs. The aim of this experiment was to determine whether maternal nutrition during late pregnancy influenced behaviour of the ewe and her lambs soon after birth, and to determine whether mid-pregnancy body condition score (BCS) influenced any behavioural response. METHODS: The experiments included ewes that were in BCS 2.0, 2.5, or 3.0 in mid-pregnancy and were fed either ad libitum or to pregnancy-maintenance requirements in late-pregnancy (day 115 until 136 in experiment one, and day 128 until 141 in experiment two). The time taken for lambs to stand, contact dam, suck from dam and follow dam was recorded three to 18 h after birth. The number of high- and low-pitched bleats emitted by the ewe and lambs was recorded, along with maternal behaviour score (MBS) of the ewe. Lambs in experiment two underwent a maternal-recognition test at 12 or 24 h. RESULTS: There were significant effects of feeding treatment on bleating behaviour of ewes and lambs, but these were inconsistent among BCS groups and between experiments. Lamb vigour behaviours were not affected by feeding treatment. In experiment one, there was no effect of feeding treatment or BCS on MBS, but in experiment two, ewes in BCS3 in mid-pregnancy had greater MBS than ewes in BCS2 in mid-pregnancy (MBS 3.1/5 vs MBS 2.1/5; p<0.05). CONCLUSION: Given there were no repeatable effects on behaviour of ewes and lambs, ad libitum feeding rather than feeding for pregnancy-maintenance requirements cannot be used to improve behaviours soon after birth of triplet-bearing ewes in BCS 2-3 and their lambs in extensive pastoral conditions.
- ItemThe pattern of breeding and management within the New Zealand Thoroughbred breeding industry 2005-2015. (II) The mare population(CSIRO Publishing, 2024-01) Chin YY; Rogers CW; Gee EK; Stafford KJ; Cameron EZContext: The New Zealand Thoroughbred breeding industry is heavily focused on producing horses for the export market and there has been a reduction in the number of horses racing in the past 20 years. The impact of these production constraints, and changes in production focus, have not been described at a national herd level. Aim: To describe the breeding management, reproductive performance, and careers of the New Zealand Thoroughbred broodmare herd during the 2005/06-2015/16 breeding seasons. Methods: The demographics, population structure, reproductive efficiency, breeding management and career descriptors of Thoroughbred mares were examined using descriptive analysis. Gestation length was modelled using a linear mixed effects model. The impact of different variables on breeding career were quantified by calculating odds ratio. Results: There was a consistent reduction in the size of the national broodmare herd over the 10 years investigated. Half of the mares not retained for breeding were mares that were breed to low-cost stallions. Despite a short (∼100 days) commercial breeding season few (20%) mares were mated early in the season (September), with most mating (70%) occurring between October and November. The 27 days mean foaling to conception interval (FCI) suggests that FCI was artificially shortened and most pregnancy was achieved within first oestrus cycle post-partum. Mare career length and lifetime productivity was positively associated with the stud fee of the first stallion that the mare was mated to and number of foals registered for racing. Conclusion: Mare replacement and loss within the national herd was disproportionately associated with mares that were producing foals for a contracting domestic racing market. There was a constricted breeding season with most mares being mated within the first oestrous cycle post-partum. Mare retention and breeding success were positively associated with the service fee of the sire and progeny that had raced, reflecting the commercial pressure of the industry on mare management. Implication: The changes in the broodmare herd and management reflects the increasing proportion of the industry focusing on breeding foals that will appeal to the export market. The economic drivers for early born foals provide management challenges as these are not aligned with the optimal reproductive season of the horse.
- ItemThe pattern of breeding and management within the New Zealand Thoroughbred breeding industry 2005-2015. 1. the stallion population(CSIRO Publishing, 2024-01) Chin YY; Rogers CW; Gee EK; Stafford KJ; Cameron EZ; Bryden WContext: There has been a contraction within the New Zealand Thoroughbred racing industry and there are limited data demonstrating how this has affected, or been reflected, within the breeding industry that supplies horses for the racing industry. A reduction in the breeding industry, to a greater extent in the sector servicing domestic rather than export market has been speculated. Aim: To describe the demographics, breeding pattern, reproductive career and workload of New Zealand Thoroughbred stallions between 2005 and 2015. Methods: The breeding records of all Thoroughbred stallions covering >10 mares during 2005/2006-2015/2016 breeding seasons and the lifetime breeding records of all the mares covered by these stallions were extracted from the New Zealand Thoroughbred Racing website. The demographics, population numbers, career pattern, and 10-year trend in market share of stallions in different stud fee categories were examined using descriptive analysis. The stallion's reproductive workload was modelled deterministically. Results: The breeding population reduced over the 10 years examined (mares by 20%, sires by 32%). This industry consolidation was almost entirely due to the 50% reduction in the number of mares mated to the low-priced stallions, which generated horses for the domestic market. The relative proportion of mares sent to medium- and high-priced stallions (breed to sell and export sector) doubled. The commercial breeding career of low- and medium-priced stallions and shuttle stallions was short (4-5 years). The number of mares covered by a stallion increased with stud fee category. Stallions covered a greater number of mares in October and November than in September and December because of the restricted opportunity to cover foaled mares early in the season, caused by the long gestation length of mares and the need to cover mares before December. Conclusions: Findings in this study support that the contraction in the New Zealand Thoroughbred breeding industry was due to a reduction in the industry sector that focuses primarily on supplying horses for domestic racing. Commercial pressure and biological constraints heavily influenced the reproductive management of the breeding industry. The breeding management of stallions during the season is heavily influenced by stallion service fee category, which reflects his book size and the commercial appeal of the resultant progeny. Implications: The contraction within the domestic sector of the breeding industry was reflected in the concurrent contraction within New Zealands domestic racing population and fewer colts and geldings entering racing. Industry breeding trends demonstrate that economic viability and optimisation of revenue depend on the breeding industry focusing on the export rather than domestic market.
- ItemValidation of a combined approach-avoidance and conditioned stimulus aversion paradigm for evaluating aversion in chickens.(PLOS, 2021-02-25) Du Plessis EW; Beausoleil NJ; Bolwell CF; Stafford KJ; Olsson IASUnderstanding animals' aversion is important to improving their welfare. Aversion is often assessed using an approach-avoidance (AA) test in which animals have to forfeit a reward if they want to avoid an event or environment presented in the same place. However, sometimes the event/environment suspected to be aversive may physically impair the animal's ability to withdraw from that place (i.e. its ability to express aversion), leading to incorrect interpretations. Combining AA with a Conditioned-Stimulus that predicts the event/environment may overcome this problem by allowing animals to demonstrate aversion without exposure to the stimulus. We aimed to validate this paradigm for testing aversion in chickens. Seven Hyline-Brown chickens were trained to obtain a food reward from a coloured bowl located in the test chamber (TC) of a two-chambered box; the reward was presented in a green bowl with an inactivated air canister or a red bowl with the canister activated to deliver an air puff. Two 5-minute tests were conducted, one with each bowl colour and both with the canister inactivated. All chickens entered TC with the green bowl. With the red bowl, two chickens entered on their first attempt, one fully entered after a partial entry (3/7 fully entered), two made only partial entries and two made no attempts to enter. Chickens spent less time in the TC with the red bowl (median 31s, IQR 7-252) compared to the green bowl (293s, IQR 290-294; p = 0.008). The higher ratio of partial to full entries, failure to enter the TC and less time spent in TC reflected chickens' aversion to the air puff, signalled by the red bowl. The paradigm allowed chickens to demonstrate aversion without exposure to the aversive stimulus during testing.
- ItemVariability in growth rates of goat kids on 16 New Zealand dairy goat farms(New Zealand Society of Animal Production, 7/07/2016) Deeming LE; Beausoleil NJ; Stafford KJ; Webster JR; Zobel GAverage daily weight gains (ADG) in early life are associated with health, welfare and future production potential of dairy animals. While this has yet to be established for goats, research in cows demonstrates a positive relationship between growth in early life and milk production (Shamay et al. 2005, Soberon et al. 2012). Early growth rates are largely determined by the management practices from birth onwards. It is therefore unsurprising that large differences in ADG under different management systems have been reported. In lambs, Mahgoub et al. (2000) reported a large range in ADG (84-154 g/day). Similarly, in calves, Bartlett et al. (2006) reported ADGs ranging from 251 g/day to 703 g/day. The ADGs reported in goats have not been as variable (152-170 g/day: Galina et al. 1995; 167-173 g/day: Goetsch et al. 2001); however, these were small, controlled studies. To our knowledge, no research has yet quantified variability in the ADG of goat kids on a large, multi-farm scale. Therefore, the aim of this study was to describe the variation in growth rates on multiple dairy goat farms in the Waikato region of NZ, providing a benchmark for dairy goat farmers.
