Browsing by Author "Kenny, David"
Adding value to cull cow beefO'Donovan, Michael; Minchin, William; Buckley, Frank; Kenny, David; Shalloo, Laurence (Teagasc, 2009-08-01)This project addressed the prospects of increasing the value of cull cow beef and examined the potential of a number of different management and dietary strategies. In Ireland, the national cow herd contributes 350,000 animals to total beef production annually, which represents 22% of all cattle slaughtered (DAF, 2007). A dominant feature of beef production in Ireland is the disposal of cows from the dairy and beef industries, the time of year at which culling occurs influences the number of cows available for slaughter. Suitability of a cow for slaughter is generally not a consideration for dairy or beef farmers.
Birth delivery method affects expression of immune genes in lung and jejunum tissue of neonatal beef calvesSurlis, Carla; McNamara, Keelan; O’Hara, Eoin; Waters, Sinead; Beltman, Marijke; Cassidy, Joseph; Kenny, David (Biomed Central, 2017-12-14)Background Caesarean section is a routine veterinary obstetrical procedure employed to alleviate dystocia in cattle. However, CS, particularly before the onset of labour, is known to negatively affect neonatal respiration and metabolic adaptation in humans, though there is little published information for cattle. The aim of this study was to investigate the effect of elective caesarean section (ECS) or normal trans-vaginal (TV) delivery, on lung and jejunal gene expression profiles of neonatal calves. Results Paternal half-sib Angus calves (gestation length 278 + 1.8 d) were delivered either transvaginally (TV; n = 8) or by elective caesarean section (ECS; n = 9) and immediately euthanized. Lung and jejunum epithelial tissue was isolated and snap frozen. Total RNA was extracted using Trizol reagent and reverse transcribed to generate cDNA. For lung tissue, primers were designed to target genes involved in immunity, surfactant production, cellular detoxification, membrane transport and mucin production. Primers for jejunum tissue were chosen to target mucin production, immunoglobulin uptake, cortisol reaction and membrane trafficking. Quantitative real-time PCR reactions were performed and data were statistically analysed using mixed models ANOVA. In lung tissue the expression of five genes were affected (p < 0.05) by delivery method. Four of these genes were present at lower (LAP, CYP1A1, SCN11α and SCN11β) and one (MUC5AC) at higher abundance in ECS compared with TV calves. In jejunal tissue, expression of TNFα, Il-1β and 1 l-6 was higher in ECS compared with TV calves. Conclusions This novel study shows that ECS delivery affects the expression of key genes involved in the efficiency of the pulmonary liquid to air transition at birth, and may lead to an increased inflammatory response in jejunal tissue, which could compromise colostral immunoglobulin absorption. These findings are important to our understanding of the viability and management of neonatal calves born through ECS.
The effects of altering milking frequency and/or diet in early lactation on the energy balance, production and reproduction of dairy cows.Murphy, J.J.; Mee, John F; McNamara, S.; Patton, J.; Kenny, David; Diskin, Michael; O'Mara, Frank P. (Teagasc, 2005-01-01)It has been suggested that negative energy balance (NEB) in the immediate post-partum period is potentially an important factor in the association between increasing milk output and declining reproductive performance. The objective of this project was to design an experimental model that could be used to impose different degrees of NEB immediately after calving and to examine the effect of this model on dry matter intake (DMI), milk production, energy balance (EB), metabolic and reproductive hormonal profiles, the onset and pattern of post-partum ovarian cyclicity and reproductive physiology around AI. Two experiments were carried out to evaluate the effects of milking frequency and diet on DMI, production, energy balance and blood metabolites and hormones in the first 4 weeks after calving and subsequent reproduction. Reducing milking frequency from either thrice or twice daily to once daily reduced DMI but also reduced milk production. This resulted in a better EB in once daily milked cows in both experiments, the reduction being significant in the first. Milk production during the 4-week treatment period was reduced by 23 and 20 percent by reducing milking frequency from thrice to once daily in experiments 1 and 2, respectively. There was a reduction of approximately 10 percent in the cumulative yield up to week 20 of lactation in experiment 1 and of approximately 9 percent in total lactation yield in experiment 2. Reducing milking frequency resulted in increased plasma glucose, insulin and IGF-1 concentrations and reduced non-esterified fatty acid (NEFA) and beta hydroxybutyrate (BHB) concentrations. Conception rates to first service or overall pregnancy rates were not different between milking frequency treatments but once daily milking resulted in a shorter interval to first ovulation than thrice daily milking, due to a higher proportion of cows on this treatment ovulating the first post-partum dominant follicle. Increasing the energy density 2 of the diet increased DMI and milk production with no consequent effect on energy balance. Logistic regression on the combined data from the two experiments showed that lower energy intake, greater NEB and lower milk protein content and were significantly associated with poorer conception to first service. Lower plasma IGF-1 concentrations in experiment 2 were also associated with a lower conception rate to first service. A third experiment which investigated protein concentration in the concentrate combined with concentrate feeding level post calving (for two groups of cows in different body condition score at calving) showed no effect of post calving diet on BCS change. Overall the results suggest that reducing milking frequency to once per day during the first 4 weeks of lactation reduces NEB and appears to be a suitable strategy for altering energy balance at this time. However, the short-term reduction in milking frequency immediately post partum reduces total lactation yields. Blood metabolite and hormonal concentrations indicate better energy balance for cows milked once daily. Increasing dietary energy density or reducing the protein content of the diet does not appear to be effective in changing energy balance in early lactation. Decreased NEB in the first 4 weeks post-partum is associated with an improved conception rate to first service.