15 research outputs found
Non-additive genetic effects for fertility traits in Canadian Holstein cattle (Open Access publication )
The effects of additive, dominance, additive by dominance, additive by additive and dominance by dominance genetic effects on age at first service, non-return rates and interval from calving to first service were estimated. Practical considerations of computing additive and dominance relationships using the genomic relationship matrix are discussed. The final strategy utilized several groups of 1000 animals (heifers or cows) in which all animals had a non-zero dominance relationship with at least one other animal in the group. Direct inversion of relationship matrices was possible within the 1000 animal subsets. Estimates of variances were obtained using Bayesian methodology via Gibbs sampling. Estimated non-additive genetic variances were generally as large as or larger than the additive genetic variance in most cases, except for non-return rates and interval from calving to first service for cows. Non-additive genetic effects appear to be of sizeable magnitude for fertility traits and should be included in models intended for estimating additive genetic merit. However, computing additive and dominance relationships for all possible pairs of individuals is very time consuming in populations of more than 200 000 animals
Meta-analysis to predict the effects of temperature stress on meat quality of poultry.
Temperature stress (TS) is a significant issue in poultry production, which has implications for animal health and welfare, productivity, and industry profitability. Temperature stress, including both hot (heat stress) and cold conditions (cold stress), is associated with increased incidence of meat quality defects such as pale, soft, and exudative (PSE) and dark, firm, and dry (DFD) meat costing poultry industries millions of dollars annually. A meta-analysis was conducted to determine the effect of ambient TS on meat quality parameters of poultry. Forty-eight publications which met specific criteria for inclusion were identified through a systematic literature review. Temperature stress was defined by extracting 2 descriptors for each treatment mean from the chosen studies: (1) temperature imposed for the experimental treatments (°C) and duration of temperature exposure. Treatment duration was categorized for analysis into acute (≤24 h) or chronic (>24 h) treatments. Meat quality parameters considered were color (L*-a*-b* scheme), pH (initial and ultimate), drip loss, cooking loss, and shear force. Linear mixed model analysis, including study as a random effect, was used to determine the effect of treatment temperature and duration on meat quality. Model evaluation was conducted by performing a k-fold cross-validation to estimate test error, and via assessment of the root mean square prediction error (RMSPE), and concordance correlation coefficient (CCC). Across both acute and chronic durations, treatment temperature was found to have a significant effect on all studied meat quality parameters. As treatment temperature increased, meat demonstrated characteristics of PSE meat and, as temperature decreased, meat demonstrated characteristics of DFD meat. The interaction between treatment temperature and duration was significant for most traits, however, the relative impact of treatment duration on the studied traits was inconsistent. Acute TS had a larger effect than chronic TS on ultimate pH, and chronic stress had a more considerable impact on color traits (L* and a*). This meta-analysis quantifies the effect of ambient TS on poultry meat quality. However, quantitative effects were generally small, and therefore may or may not be of practical significance from a processing perspective
Phenylalanine flux and gastric emptying are not affected by replacement of casein with whey protein in the diet of adult cats consuming frequent small meals
Non-additive genetic effects for fertility traits in Canadian Holstein cattle (Open Access publication)
The effects of additive, dominance, additive by dominance, additive by
additive and dominance by dominance genetic effects on age at first service,
non-return rates and interval from calving to first service were estimated.
Practical considerations of computing additive and dominance relationships
using the genomic relationship matrix are discussed. The final strategy
utilized several groups of 1000 animals (heifers or cows) in which all
animals had a non-zero dominance relationship with at least one other animal
in the group. Direct inversion of relationship matrices was possible within
the 1000 animal subsets. Estimates of variances were obtained using
Bayesian methodology via Gibbs sampling. Estimated non-additive genetic
variances were generally as large as or larger than the additive genetic
variance in most cases, except for non-return rates and interval from
calving to first service for cows. Non-additive genetic effects appear to be
of sizeable magnitude for fertility traits and should be included in models
intended for estimating additive genetic merit. However, computing additive
and dominance relationships for all possible pairs of individuals is very
time consuming in populations of more than 200 000 animals
A Cross-Sectional Study on the Prevalence of Footpad Dermatitis in Canadian Turkeys
Footpad dermatitis (FPD) can be a prevalent issue in commercial turkey production. This study aimed to identify the bird, housing, and management-related factors associated with the prevalence of FPD in the Canadian turkey flocks. A questionnaire and flock health scoring system were developed and disseminated to ~500 commercial turkey farmers across Canada. Farmers were asked to score FPD on a subset of 30 birds within their flock using a 0–2 scoring scale based on severity. The prevalence of FPD in the flock was calculated as the percentage of affected birds (score 1 or 2). A multivariate linear regression modeling was used to identify the factors associated with the prevalence of FPD. Four variables were included in the final model and accounted for 26.7% of the variation in FPD prevalence among the flocks. FPD prevalence was higher with increasing bird weight (3.6 ± 1.13), higher in flocks bedded with straw (12.1 ± 7.9), higher in flocks where birds were picked up less frequently during daily inspections (11.6 ± 8.10), and higher in flocks that used feed/water additives to reduce litter moisture (20.5 ± 10.59). These findings are a preliminary exploratory assessment of risk factors related to FPD prevalence on Canadian turkey farms. While these findings emphasize the importance of litter management and the stockperson, estimates and P-values from this study should be interpreted with caution. Further, longitudinal studies with the identified variables are required to better determine their influence on FPD
A risk factor analysis of health traits in turkeys (Meleagris gallopavo) on Canadian farms
A Pilot Study to Determine Whether a Tongue-Activated Liquid Dispenser Would Mitigate Abnormal Behavior in Pasture-Restricted Horses
Protein Mass-Modulated Effects in the Catalytic Mechanism of Dihydrofolate Reductase: Beyond Promoting Vibrations
The role of fast protein dynamics
in enzyme catalysis has been
of great interest in the past decade. Recent “heavy enzyme”
studies demonstrate that protein mass-modulated vibrations are linked
to the energy barrier for the chemical step of catalyzed reactions.
However, the role of fast dynamics in the overall catalytic mechanism
of an enzyme has not been addressed. Protein mass-modulated effects
in the catalytic mechanism of <i>Escherichia coli</i> dihydrofolate
reductase (ecDHFR) are explored by isotopic substitution (<sup>13</sup>C, <sup>15</sup>N, and non-exchangeable <sup>2</sup>H) of the wild-type
ecDHFR (<i>l</i>-DHFR) to generate a vibrationally perturbed
“heavy ecDHFR” (<i>h</i>-DHFR). Steady-state,
pre-steady-state, and ligand binding kinetics, intrinsic kinetic isotope
effects (KIE<sub>int</sub>) on the chemical step, and thermal unfolding
experiments of both <i>l</i>- and <i>h</i>-DHFR
show that the altered protein mass affects the conformational ensembles
and protein–ligand interactions, but does not affect the hydride
transfer at physiological temperatures (25–45 °C). Below
25 °C, <i>h</i>-DHFR shows altered transition state
(TS) structure and increased barrier-crossing probability of the chemical
step compared with <i>l</i>-DHFR, indicating temperature-dependent
protein vibrational coupling to the chemical step. Protein mass-modulated
vibrations in ecDHFR are involved in TS interactions at cold temperatures
and are linked to dynamic motions involved in ligand binding at physiological
temperatures. Thus, mass effects can affect enzymatic catalysis beyond
alterations in promoting vibrations linked to chemistry