Effect of plane of nutrition during the first 12 weeks of life on growth, metabolic and reproductive hormone concentrations, and testicular relative mRNA abundance in preweaned Holstein Friesian bull calves
posted on 2022-12-13, 09:39authored byStephen P. Coen, Kate Keogh, Colin J. Byrne, Patrick Lonergan, Sean FairSean Fair, M.A. Crowe, David A. Kenny
The objective of this study was to examine the effect of nutrition during the first 12 wk of life on aspects of the physiological and
transcriptional regulation of testicular and overall sexual development in the bull calf. Holstein Friesian bull calves with a mean
(SD) age and bodyweight of 17.5 (2.85) d and 48.8 (5.30) kg, respectively, were assigned to either a high (HI; n = 15) or moderate
(MOD; n = 15) plane of nutrition and were individually fed milk replacer and concentrate to achieve overall target growth rates of
at least 1.0 and 0.5 kg/d, respectively. Throughout the trial, animal growth performance, feed intake, and systemic concentrations
of metabolites, metabolic hormones, and reproductive hormones were assessed. Additionally, pulsatility of reproductive
hormones (luteinizing hormone, follicle-stimulating hormone, and testosterone) was recorded at 15-min intervals during a 10-h
period at 10 wk of age. At 87 ± 2.14 d of age, all calves were euthanized, testes were weighed, and testicular tissue was harvested.
Differential expression of messenger ribonucleic acid (mRNA) candidate genes involved in testicular development was examined
using quantitative polymerase chain reaction assays. All data were analyzed using the MIXED procedure in Statistical Analysis
Software using terms for treatment as well as time for repeated measures. Blood metabolites and metabolic hormones generally
reflected the improved metabolic status of the calves on the HI plane of nutrition though the concentrations of reproductive
hormones were not affected by diet. Calves on the HI diet had greater mean (SED) slaughter weight (112.4 vs. 87.70 [2.98] kg;
P < 0.0001) and testicular tissue weight (29.2 vs. 20.1 [2.21] g; P = 0.0003) than those on the MOD diet. Relative mRNA abundance
data indicated advanced testicular development through upregulation of genes involved in cellular metabolism (SIRT1;
P = 0.0282), cholesterol biosynthesis (EBP; P = 0.007), testicular function (INSL3; P = 0.0077), and Sertoli cell development (CLDN11;
P = 0.0054) in HI compared with MOD calves. In conclusion, results demonstrate that offering dairy-bred male calves a high plane
of nutrition during the first 3 mo of life not only improves growth performance and metabolic status but also advances testicular
development consistent with more precocious sexual maturation.