This thesis consists of a series of studies which are aimed at the development of systems to improve the health and performance of dairy-origin beef. Specifically, this thesis addresses four key knowledge gaps which were identified following a comprehensive review of the scientific literature. The objectives were to:
1. Examine the effect of calf jackets during the rearing period on the health, performance and skin surface temperature of calves.
2. Investigate the effect of behaviour in bulls on rumen temperature, and assess the extent to which this would influence the accuracy of prediction of ill health.
3. Evaluate the effect of production system on the health, performance and carcass characteristics of Holstein bulls slaughtered under 16 months.
4. Evaluate the use of rumen temperature as a novel welfare indicator and predictor of meat quality during the pre-slaughter phase.
Chapter two investigates the use of calf jackets in a commercial dairy-origin beef system. This study involved five batches of calves, over the duration of one year in order to take into account the effect of seasonality. Four treatment groups were assigned within each batch; a control group with no jacket, and three jacket groups which varied according to the time the jacket was worn. Mean ambient temperatures ranged from 6.16°C in batch four to 16.93°C in batch two. The study which involved a total of 422 calves found no significant difference in calf health or performance due to calf jacket treatment. Skin surface temperature was also assessed, with that of jacket calves being 4.31°C greater (P<0.001) than that of non-jacket calves.
Chapter three examines the effect of 10 behaviour classifications on rumen temperature while bulls were at pasture and also housed at the beginning of the finishing period. Furthermore, the effect of diet (level of concentrate supplementation) on rumen temperature was also assessed. Rumen temperature was significantly elevated (P<0.001) for three of the behaviours recorded; the recipient of agonistic or sexual behaviour, stationary and consuming concentrates. However, the level of concentrate supplementation did not have any effect on mean rumen temperature throughout the duration of the study. Drinking caused a significant (P<0.001) decline in rumen temperature. Although variations in rumen temperature were apparent in this study, all mean temperatures were within the normal range for healthy cattle.
Chapter four examines the effect of production system on the health, performance and carcass characteristics of Holstein bulls. This study which consisted of 224 bulls, also took into account the effects of year and whether bulls were autumn or spring born, in a 2(year)x2(season)x4(production system) factorial design experiment. Production systems differed during the grower period consisting of; housed with ad libitum concentrates (HA), while the three remaining treatments were grazed with various levels of concentrate supplementation 0kg (G), 2kg (G2), and ad libitum (GA). Bulls were all housed for finishing on an ad libitum concentrate and grass silage diet, and slaughtered at a mean age of 15.5 months. Performance was greatest in year one (P<0.001) and for AB bulls (P<0.001). GA bulls had the greatest DMI during both the grower (P<0.001) and finishing period (P<0.001), while that of G bulls was the lowest. Furthermore, G bulls had the poorest performance during the grower period (P<0.001), yet through compensatory growth achieved the greatest DLWG during the finishing period (P<0.001). Bulls on the GA and HA production systems had the greatest carcass weight (P<0.001). There were minimal effects on carcass characteristics and meat quality, and no effect on animal health.
Chapter five assesses the use of rumen temperature as a novel welfare indicator and predictor of meat quality during the pre-slaughter phase. This was an observational study, involving 42 Holstein bulls which were transported to a commercial abattoir. Rumen temperature, cortisol, creatine kinase and lactate dehydrogenase were all significantly elevated (P<0.001) during the pre-slaughter phase. Bulls with an ultimate pH >6.2 had the greatest (P<0.001) maximum rumen temperature during lairage of 41.16°C. Results indicated that a combination of rumen temperature and haematological variables could be used to predict meat quality; with the model for ultimate pH having the greatest R2 value (53.1).
In conclusion, the research within this thesis provided valuable insights into the commercial use of calf jackets, and the evaluation of bull beef production systems. Through the dissemination of these findings to producers, this research could influence current industry practices and thus have direct benefits for industry. Furthermore, the novel approach of establishing the impact of behaviour on rumen temperature, together with the prediction of meat quality from pre-slaughter rumen temperature has identified some very interesting relationships. These initial findings have highlighted areas of future research, which have the potential to provide a better understanding of the uses of rumen temperature boluses in both research and industry.
|Date of Award||Jul 2020|
- Queen's University Belfast
|Sponsors||Department of Agriculture, Environment and Rural Affairs|
|Supervisor||Francis Lively (Supervisor), Gareth Arnott (Supervisor) & Katerina Theodoridou (Supervisor)|