The aim of this study was to examine the effect of plane of nutrition (1) during the first 6 mo of life and (2) from 6 mo of age to puberty on early growth characteristics, age at puberty, and postpubertal semen production in Holstein-Friesian bulls. Holstein-Friesian bull calves (n = 83) with a mean (standard deviation) age and body weight of 17 (4.4) d and 52 (6.2) kg, respectively, were assigned to a high (Hi) or low (Lo) plane of nutrition for the first 6 mo of life. The Hi and Lo calves received 1,200 and 450 g of milk replacer, respectively; Hi calves were fed concentrate ad libitum and Lo were fed a maximum of 1 kg concentrate daily, and concentrate allowances remained the same after weaning. At 24 wk of age, bulls were reassigned within treatment to either remain on the same diet or to switch to the opposite diet until puberty, resulting in 4 treatment groups: Hi-Hi, Hi-Lo, Lo-Lo, and Lo-Hi. After puberty, all bulls were fed a moderate plane of nutrition until 60 wk of age; thereafter, the diet was ad libitum concentrates until slaughter at 72 wk of age. Bulls were weighed weekly before weaning and every 2 wk after weaning. Scrotal circumference (SC) was measured every 2 wk, beginning at 15 wk of age. Beginning at a SC of 24 cm, electro-ejaculation was carried out every 2 wk to establish the onset of puberty. Semen collection continued monthly after puberty. Thermal images of the scrotum were taken monthly from 28 to 36 wk of age. Scrotal skin thickness (SST) was measured monthly (from 16 wk of age to puberty) using a digital calipers. Bulls on the Hi diet had a higher scrotal temperature and SST at each time point than those on the Lo diet. Average daily gain (ADG) was greatest in Hi-Hi bulls, with Hi-Lo and Lo-Hi having similar ADG but both being greater than Lo-Lo. Bulls on the Hi diet pre-6 mo of age were younger at puberty, regardless of diet offered post-6 mo of age. Bulls offered a Hi diet post-6 mo were heavier at puberty. Neither scrotal temperature nor dietary treatment affected postpubertal semen production variables. In conclusion, a high plane of nutrition during the first 6 mo of age hastened the onset of puberty and the availability of saleable semen, regardless of plane of nutrition post-6 mo of age.

No abstract

In reproductive hens, a feed restriction is an usual practice to improve metabolic and reproductive disorders. However, it acts a stressor on the animal. In mammals, grape seed extracts (GSE) reduces oxidative stress. However, their effect on endocrine and tissue response need to be deepened in reproductive hens. Here, we evaluated the effects of time and level of GSE dietary supplementation on growth performance, viability, oxidative stress and metabolic parameters in plasma and metabolic tissues in reproductive hens and their offsprings. We designed an in vivo trial using 4 groups of feed restricted hens: A (control), B and C (supplemented with 0.5% and 1% of the total diet composition in GSE since week 4, respectively) and D (supplemented with 1% of GSE since the hatch). In hens from hatch to week 40, GSE supplementation did not affect food intake and fattening whatever the time and dose of supplementation. Body weight was significantly reduced in D group as compared to control. In all hen groups, GSE supplementation decreased plasma oxidative stress index associated to a decrease in the mRNA expression of the NOX4 and 5 oxidant genes in liver and muscle and an increase in SOD mRNA expression. This was also associated to decreased plasma chemerin and increased plasma adiponectin and visfatin levels. Interestingly, maternal GSE supplementation increased the live body weight and viability of chicks at hatching and 10 days of age. This was associated to a decrease in plasma and liver oxidative stress parameters. Taken together, GSE maternal dietary supplementation reduces plasma and tissue oxidative stress associated to modulation of adipokines without affecting

Maternal nutritional perturbation during gestation influences fetal development which, in turn, can affect postnatal growth, gonad development, gamete quality, and health of the offspring. The objective of this study was to determine whether maternal diet during the pre-pubertal phase would induce modifications in future male fetal reproductive development. Angus×Holstein-Friesian heifers (n=80) with a mean (±s.d.) age of 141±8d and bodyweight (BW) of 119±23kg had unrestricted access to a perennial ryegrass dominated sward supplemented with either 0.5kg of concentrate daily to achieve an average daily gain (ADG) of 0.50kg (moderate, MOD) or concentrate ad libitum to achieve an ADG of >1.0kg (high, HI). Heifers were offered these divergent dietary regimens from 4.5 to 8.5 months of age, after which they were all offered a moderate plane of nutrition. Heifers were bred to a synchronised oestrus at a mean age of 502±8.2d and mean BW of 360±46.7kg using semen from a single proven sire. Transrectal uterine ultrasonography was carried out 63 days post-AI to determine pregnancy and fetal sex; a cohort of heifers reflective of group average BW and age and carrying male fetuses were slaughtered on Day 100 of gestation (HI: n=10; MOD: n=12). Fetal crown–rump length and weight were recorded. One testis was snap frozen for RNA sequencing and the other was processed for stereology. Mean (±s.d.) fetal crown–rump length and weight were 19.5±0.69cm and 314.6±33.6g, respectively, and did not differ between groups. RNA sequencing revealed 45 differentially expressed genes (DEGs) between groups, 44 of which were upregulated in the HI group. A total of 29 biochemical pathways were identified as significantly enriched (P<0.05), six of which were predicted to be involved in the development of the reproductive tract based on several DEGs. Histological analysis revealed greater (P<0.05) fetal testicular interstitial tissue density in the MOD group and a strong tendency towards increased seminiferous tubule density (P=0.06) in the HI group. In conclusion, offering a high plane of nutrition during the prepubertal period not only increases the rate of sexual development in the heifer but also induces latent in utero modifications to the testicular development of their subsequent male progeny. The consequences for postnatal development of male progeny remain to be elucidated. This research was supported by Science Foundation Ireland (16/IA/4474).