Animal Industry Report: Volume 661, Issue 1
Host genetic differences in viral load (VL) and weight gain (WG) during porcine reproductive and respiratory syndrome virus (PRRSV) challenge were assessed for thirteen trials of ~200 commercial crossbred piglets each, from several different commercial suppliers. Piglets were experimentally infected with PRRSV isolates NVSL-97-7895 (NVSL) or KS-2006-72109 (KS06). VL and WG were moderately heritable and were antagonistically related for both virus isolates. The genetic correlation of host response to NVSL with host response to KS06 was high for both VL and WG. Consistent with previous findings, animals that were heterozygous (AB) for the WUR10000125 (WUR) marker on Chromosome 4 (SSC4) had significantly lower VL than their AA counterparts when infected with either virus isolate; however, a significant increase in WG was only observed when piglets were infected with the NVSL isolate. These results suggest that selecting for increased resistance or reduced susceptibility to PRRSV may be effective across virus isolates. Selecting for the AB genotype for WUR is expected to reduce VL across PRRSV isolates but its effect on WG during infection may differ between virus isolates.
The effects of pairing a low quality forage with increasing metabolizable protein (MP) supplementation from a moderately abundant rumen undegradable protein (RUP) source (corn gluten meal; 62% RUP) on essential plasma amino acid (AA) concentrations were evaluated in a 60-day trial. Non-pregnant, non-lactating cows (n=24) were offered ad libitum access to cornstalks and fed 1 of 3 isocaloric diets (0.48 NEm/lb) and supplemented primarily with corn gluten meal to provide 100% MP requirements (CON), 125% MP requirements (MP125), or 150% MP requirements (MP150). It was observed that increasing concentrations of MP in the diet from a moderately abundant RUP source increased the percent of essential AA, ketogenic AA, branched-chain AA and urea cycle AA in plasma. Also, as a percent of total AA, glycogenic AA were decreased with increased MP supplementation. Therefore, increasing supplementation of MP can the shift essential AA profiles of beef cows when fed with low quality forage.
The objective of this study was to examine potential signs, causal factors and treatment interventions for camelids displaying Aberrant Behavior Syndrome (ABS), also known as Berserk Male Syndrome. A survey was developed for camelid owners and veterinarians with camelid experience using Survey Monkey software. Respondents were asked to describe the behaviors associated with the most recent case of ABS they were involved with, information about the animal displaying ABS, and evaluation of the efficacy of treatment interventions used. The majority of respondents identified a general demographic of an intact male camelid raised by its biological mother with daily or weekly handing by humans.
Aggressive behavior emerged at one to three years of age, and was directed more frequently at humans than at other animals. Treatment interventions included behavioral modification, castration, moving and/or isolating the animal. All treatments had a higher rate of failure than success. The results of this survey indicate a need for research to identify causal factors and treatments for this behavioral disorder.
Foetal calves produce sex hormones that can enter the maternal bloodstream. Male calves typically have longer gestations than female calves resulting in shorter lactations in pastoral production systems. Both of these phenomena could influence milk yields of the dam. North American and French studies have reported conflicting results as to the size of calf gender effects on milk yield. This study used a dataset from New Zealand dairy cattle to fit calf gender effects and quantify the impact of including calf gender when estimating breeding values. The regressions of lactation yield on days in milk were different for second parity cows according to whether the cows had produced male or female calves. The gender of a cow’s second calf had an effect on second lactation milk yield in Holstein Friesians. There was minimal re-ranking of animals when calf gender was included in the model used for breeding value estimation and the expected genetic gain was similar with and without calf gender included in the analytical model.
The relationships between body condition score (BCS) observed during the first 45 days of lactation and two measures of feed efficiency, residual feed intake (RFI) and gross efficiency (GE) defined as milk energy / DMI, measured during mid-lactation were assessed in 255 first lactation Holstein cows. No significant differences in BCS at calving and at approximately 40 days in milk (DIM) nor in BCS loss during the first 25 and first 45 DIM were observed between the most feed efficient and feed inefficient cows when either RFI or GE was used as the measure of feed efficiency. However when feed efficiency was measured as GE, feed efficient cows had significantly lower BCS at 40 DIM. Our findings suggest that selection based on RFI as a measure of feed efficiency during mid-lactation should not impact BCS loss during early lactation.