Animal & Bioscience
http://hdl.handle.net/11019/11
2024-03-13T19:04:32ZImpact of birth and rearing type, as well as inaccuracy of recording, on pre-weaning lamb phenotypic and genetic merit for live weight1
http://hdl.handle.net/11019/3688
Impact of birth and rearing type, as well as inaccuracy of recording, on pre-weaning lamb phenotypic and genetic merit for live weight1
McHugh, N.; Pabiou, T.; McDermott, K.; Wall, E.; Berry, D. P.
The objective of the present study was
to quantify the impact of the systematic environmental
effects of both birth and rearing type on pre-weaning
lamb live weight, and to evaluate the repercussions of
inaccurate recording of birth and rearing type on subsequent genetic evaluations. A total of 32,548 birth
weight records, 35,770 forty-day weight records and
32,548 records for average daily gain (ADG) between
birth and 40-day weight from the Irish national sheep
database were used. For each lamb, a new variable,
birth-rearing type, reflecting both the birth and rearing type of a lamb was generated by concatenating
both parameters. The association between birth-rearing type and birth weight, 40-day weight, and ADG
was estimated using linear mixed models. The repercussions of inaccurate recording of birth type were
determined by quantifying the impact on sire estimated breeding value (EBV; with an accuracy of ≥
35%), where one of the lambs born in a selection of
twin litter births was assumed to have died at birth
but the farmer recorded the birth and rearing type
as a singleton. The heaviest mean birth weight was
associated with lambs born and subsequently reared
as singles (5.47 kg); the lightest mean birth weight
was associated with lambs born and reared as triplets (4.10 kg). The association between birth-rearing
type and 40-day weight differed by dam parity (P <
0.001). Lambs reared by first parity dams as singles,
irrespective of birth type were, on average, heavier at
40-day weighing than lambs reared as multiples, but
as parity number increased, single-born lambs reared
as twins outperformed triplet-born lambs reared as
singles. Irrespective of the trait evaluated, the correlation between sire EBV estimated from the accurately
recorded data and sire EBV estimated from the data
with recording errors was strong ranging from 0.93
(birth weight) to 0.97 (ADG). The EBV for sires
with progeny data manipulated were 0.14 kg, 0.34
kg and 5.56 g/d less for birth weight, 40-day weight
and ADG, respectively, compared to their equivalent EBV calculated using accurately recorded data.
Results from this study highlight the importance of
precise recording of birth-rearing type by producers
for the generation of accurate genetic evaluations.
peer-reviewed
2017-04-01T00:00:00ZIs TB Testing Associated With Increased Blood Interferon-Gamma Levels?
http://hdl.handle.net/11019/3683
Is TB Testing Associated With Increased Blood Interferon-Gamma Levels?
Kennedy, Aideen E.; O’Mahony, Jim; Byrne, Noel; MacSharry, John; Sayers, Riona G.
The Republic of Ireland reports a relatively low prevalence of Johne’s disease (JD)
compared to international counterparts. Postulated reasons for this include a lower
average herd size and a grass-based production system. Ireland also engages in high
levels of bovine tuberculosis (bTB) testing. As interferon-gamma (IFN-γ) is believed to
play a key role in protecting against JD, it is our hypothesis that administration of purified
protein derivative (PPD), as part of the bTB test, is associated with a systemic increase
in IFN-γ production, which may potentially limit clinical progression of the disease.
We studied 265 cows (202 Friesian and 63 “Non-Friesian,” e.g., JerseyX, Norwegian Red)
to assess IFN-γ levels and Mycobacterium avium subspecies paratuberculosis (MAP)
antibody response before and after the bTB test. As part of the compulsory annual bTB
test, avian and bovine PPD were administered at two separate cervical sites. To assess
IFN-γ production, blood samples were taken before and 72 h after PPD administration.
MAP antibody response was assessed before and 10 days post-PPD administration.
A significant increase in MAP antibody response was identified post-bTB compared to
pre-bTB response (p < 0.001). Additionally, IFN-γ production significantly increased at
the post-bTB time point (p < 0.001) compared to the pre-bTB test readings. This may
indicate a beneficial effect of bTB testing in controlling JD.
peer-reviewed
2017-10-23T00:00:00ZGenomic identification, expression profiling, and functional characterization of CatSper channels in the bovine†
http://hdl.handle.net/11019/3681
Genomic identification, expression profiling, and functional characterization of CatSper channels in the bovine†
Johnson, Gillian P.; English, Anne-Marie; Cronin, Sinead; Hoey, David A.; Meade, Kieran G.; Fair, Sean
Cation channels of sperm (CatSper) are sperm-specific calcium channels with identified roles in the regulation of sperm function in humans, mice, and horses. We sought to employ a comparative genomics approach to identify conserved CATSPER genes in the bovine genome, and profile their expression in reproductive tissue. We hypothesized that CATSPER proteins expressed in bull testicular tissue mediates sperm hyperactivation and their rheotactic response in the reproductive tract of the cow. Bioinformatic analysis identified all four known CATSPER genes (CATSPER 1–4) in the bovine genome, and profiling by quantitative real-time polymerase chain reaction identified site-specific variation in messenger ribonucleic acid (mRNA) expression for all four genes along the reproductive tract of the bull. Using a novel antibody against CATSPER 1, protein expression was confirmed and localized to the principal piece of bull sperm, in agreement with what has been reported in other species. Subsequent treatment of bull sperm with either the calcium chelator ethylene glycol tetraacetic acid; mibefradil, a specific blocker of CatSper channels in human sperm; or CATSPER1 antibody all significantly inhibited caffeine-induced hyperactivation and the rheotactic response, supporting the concept that the calcium influx occurs via CatSper channels. Taken together, the work here provides novel insights into expression and function of CatSper channels in bull testicular tissue and in the function of ejaculated sperm.
peer-reviewed
2017-07-26T00:00:00ZThe creation and evaluation of a model to simulate the probability of conception in seasonal-calving pasture-based dairy heifers
http://hdl.handle.net/11019/3676
The creation and evaluation of a model to simulate the probability of conception in seasonal-calving pasture-based dairy heifers
Fenlon, Caroline; O’Grady, Luke; Butler, Stephen; Doherty, Michael L.; Dunnion, John
Background: Herd fertility in pasture-based dairy farms is a key driver of farm economics. Models for predicting
nulliparous reproductive outcomes are rare, but age, genetics, weight, and BCS have been identified as factors
influencing heifer conception. The aim of this study was to create a simulation model of heifer conception to
service with thorough evaluation.
Methods: Artificial Insemination service records from two research herds and ten commercial herds were provided
to build and evaluate the models. All were managed as spring-calving pasture-based systems. The factors studied
were related to age, genetics, and time of service. The data were split into training and testing sets and
bootstrapping was used to train the models. Logistic regression (with and without random effects) and generalised
additive modelling were selected as the model-building techniques. Two types of evaluation were used to test the
predictive ability of the models: discrimination and calibration. Discrimination, which includes sensitivity, specificity,
accuracy and ROC analysis, measures a model’s ability to distinguish between positive and negative outcomes.
Calibration measures the accuracy of the predicted probabilities with the Hosmer-Lemeshow goodness-of-fit,
calibration plot and calibration error.
Results: After data cleaning and the removal of services with missing values, 1396 services remained to train the
models and 597 were left for testing. Age, breed, genetic predicted transmitting ability for calving interval, month
and year were significant in the multivariate models. The regression models also included an interaction between
age and month. Year within herd was a random effect in the mixed regression model. Overall prediction accuracy
was between 77.1% and 78.9%. All three models had very high sensitivity, but low specificity. The two regression
models were very well-calibrated. The mean absolute calibration errors were all below 4%.
Conclusion: Because the models were not adept at identifying unsuccessful services, they are not suggested for
use in predicting the outcome of individual heifer services. Instead, they are useful for the comparison of services
with different covariate values or as sub-models in whole-farm simulations. The mixed regression model was
identified as the best model for prediction, as the random effects can be ignored and the other variables can be
easily obtained or simulated.
peer-reviewed
2017-11-22T00:00:00Z