Influence of gestation housing on sow behavior and fertility

Contains fulltext : 56272.pdf (publisher's version ) (Open Access)Objective: To examine the effect of group housing sows on their behavior and fertility. Materials and methods: In Experiment One, at 65 to 70 days of gestation, 96 sows were assigned by parity to individual or group housing and observed for aggressive encounters during three 1.5-hour time blocks immediately after relocation and 1 day later. On the third day, feeding-time aggression was observed during two 30-minute feeding periods, starting when feed was dropped. Saliva samples obtained from unrestrained sows 1 day before and after relocation were assayed for cortisol concentrations. In Experiment Two, 937 mixed-parity sows in 10 weekly breeding groups were either housed in groups of approximately 50 (n = 462) or individually housed in gestation stalls (n = 475). For 140 individually-housed and 330 group-housed sows, backfat depths at the P2 position were determined using A-mode ultrasonography at gestation days 55 to 60, at farrowing, and at weaning. Results: Group-housed sows were involved in more aggressive encounters than stall-housed animals (P < .05). Aggressive encounters per hour were more numerous in grouped sows during feeding on day 3 than during the day of grouping (P < .001). Salivary cortisol concentrations were higher in grouped sows, but differences between pre-and post-relocation concentrations were not correlated with levels of aggression. There was no effect of housing on backfat depths or sow fertility. Implication: If sows are grouped during gestation, particular attention should be directed toward feeding management to avoid excessive aggression and possible adverse effects on welfare

Influence of gestation housing on sow behavior and fertility

Objective: To examine the effect of group housing sows on their behavior and fertility. Materials and methods: In Experiment One, at 65 to 70 days of gestation, 96 sows were assigned by parity to individual or group housing and observed for aggressive encounters during three 1.5-hour time blocks immediately after relocation and 1 day later. On the third day, feeding-time aggression was observed during two 30-minute feeding periods, starting when feed was dropped. Saliva samples obtained from unrestrained sows 1 day before and after relocation were assayed for cortisol concentrations. In Experiment Two, 937 mixed-parity sows in 10 weekly breeding groups were either housed in groups of approximately 50 (n = 462) or individually housed in gestation stalls (n = 475). For 140 individually-housed and 330 group-housed sows, backfat depths at the P2 position were determined using A-mode ultrasonography at gestation days 55 to 60, at farrowing, and at weaning. Results: Group-housed sows were involved in more aggressive encounters than stall-housed animals (P < .05). Aggressive encounters per hour were more numerous in grouped sows during feeding on day 3 than during the day of grouping (P < .001). Salivary cortisol concentrations were higher in grouped sows, but differences between pre-and post-relocation concentrations were not correlated with levels of aggression. There was no effect of housing on backfat depths or sow fertility. Implication: If sows are grouped during gestation, particular attention should be directed toward feeding management to avoid excessive aggression and possible adverse effects on welfare

Genomic wide-selection for tick resistance in Hereford and Braford cattle via reaction norm models.

ABSTRACT.The objective of this study was to compare a conventional genomic model (GBLUP) and its extension to a linear reaction norm model (GLRNM) specifying genotype by environment interaction (G*E) for tick resistance in Brazilian cattle. Tick counts (TC) from 4,363 Hereford and Braford cattle from 146 contemporary groups (CG) were available of which 3,591 animals had BovineSNP50 Illumina v2 BeadChip genotypes. The reaction norm covariate was based on CG estimates of TC from a first-step model. Analysis was conducted based on adapting the single step GBLUP/REML procedure. Five-fold cross validation based on K-means and random partitioning was used to compare the fit of the two models. Cross validation correlations were strong and not significantly different between models for either partitioning strategy. Nevertheless, it seems apparent that G*E for tick infestation exists and can captured by GLRNM models

Harnessing the genetics of the modern dairy cow to continue improvements in feed efficiency

Feed efficiency, as defined by the fraction of feed energy or dry matter captured in products, has more than doubled for the US dairy industry in the past 100 yr. This increased feed efficiency was the result of increased milk production per cow achieved through genetic selection, nutrition, and management with the desired goal being greater profitability. With increased milk production per cow, more feed is consumed per cow, but a greater portion of the feed is partitioned toward milk instead of maintenance and body growth. This dilution of maintenance has been the overwhelming driver of enhanced feed efficiency in the past, but its effect diminishes with each successive increment in production relative to body size and therefore will be less important in the future. Instead, we must also focus on new ways to enhance digestive and metabolic efficiency. One way to examine variation in efficiency among animals is residual feed intake (RFI), a measure of efficiency that is independent of the dilution of maintenance. Cows that convert feed gross energy to net energy more efficiently or have lower maintenance requirements than expected based on body weight use less feed than expected and thus have negative RFI. Cows with low RFI likely digest and metabolize nutrients more efficiently and should have overall greater efficiency and profitability if they are also healthy, fertile, and produce at a high multiple of maintenance. Genomic technologies will help to identify these animals for selection programs. Nutrition and management also will continue to play a major role in farm-level feed efficiency. Management practices such as grouping and total mixed ration feeding have improved rumen function and therefore efficiency, but they have also decreased our attention on individual cow needs. Nutritional grouping is key to helping each cow reach its genetic potential. Perhaps new computer-driven technologies, combined with genomics, will enable us to optimize management for each individual cow within a herd, or to optimize animal selection to match management environments. In the future, availability of feed resources may shift as competition for land increases. New approaches combining genetic, nutrition, and other management practices will help optimize feed efficiency, profitability, and environmental sustainability

Genotype by environment interaction for tick resistance of Hereford and Braford beef cattle using reaction norm models.

ABSTRACT.Background.The cattle tick is a parasite that adversely affects livestock performance in tropical areas. Although countries such as Australia and Brazil have developed genetic evaluations for tick resistance, these evaluations have not considered genotype by environment (G*E) interactions. Genetic gains could be adversely affected, since breedstock comparisons are environmentally dependent on the presence of G*E interactions, particularly if residual variability is also heterogeneous across environments. The objective of this study was to infer upon the existence of G*E interactions for tick resistance of cattle based on various models with different assumptions of genetic and residual variability.© Mota et al. 201