Plane of nutrition before and after 6 months of age in Holstein-Friesian bulls: I. Effects on performance, body composition, age at puberty, and postpubertal semen production

Abstract

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.

Effect of increased intake of milk replacer in young calves on growth and the neonatal mode of action of IGF-I.

“…We have reported that increasing consumption of commercial milk replacer in suckling Holstein bull calves leads to an overall increase in body growth with improved feed e ciency, and speci c changes in growth rates of abdominal organs and tissues [9]. Improved body, carcass and ST muscle weights at 42 days of age in calves on a higher plane of nutrition in this study (Table 2) supports the work of Byrne et al [2] and others [11,1]. While the increased body weight gain is not always sustained into adulthood, suckling bull and heifer calves on a higher plane of nutrition reach puberty at an earlier age and producers see an economic advantage over later maturing livestock.…”

“…An increased plane of nutrition in the preweaning period can promote growth in replacement heifers so that they reach puberty and calve at an earlier age; and produce more milk at rst lactation [1]. Bull calves on a high plane of nutrition in their rst six months of life reached puberty at an earlier age than bull calves on a low plane of nutrition [2] and this hastened the availability of salable semen. Beef cattle on a higher plane of nutrition in the preweaning period enter the feedlot at an earlier age and gain weight more e ciently than older aged cattle.…”

Accelerating Onset of Puberty Through Modification of Early Life Nutrition Induces Modest but Persistent Changes in Bull Sperm DNA Methylation Profiles Post-puberty

“…The management of the bulls has been described in detail (Byrne et al, 2018a). Diets were designed using National Research Council (NRC) guidelines (2001).…”

Parental Effects on Epigenetic Programming in Gametes and Embryos of Dairy Cows

“…Enhanced pre-pubertal nutrition elevates the percentage of progressively motile and upregulates mitochondrial function in sperm of post-pubertal dairy bulls ( Johnson et al, 2020 ). In contrast, low planes of nutrition of young Holstein-Friesian bulls resulted in the retarded onset of puberty ( Byrne et al, 2018 ). Although epigenetic studies related to bull metabolic status is still missing, DNA methylation and histone modifications patterns were both reported to be associated with bull fertility ( Verma et al, 2015 ; Kropp et al, 2017 ; Kutchy et al, 2018 ; Capra et al, 2019 ; Ugur et al, 2019 ).…”