Interaction of dietary energy source and body weight gain during the juvenile period on metabolic endocrine status and age at puberty in beef heifers1

Abstract

Using a previously established model for nutritional acceleration of puberty, beef heifers ( = 48; 1/2 Angus × 1/4 Hereford × 1/4 Brahman) were used in a replicated 2 × 2 factorial design to examine the effects of diet type (high forage [HF] vs. high concentrate [HC]) and rate of BW gain (low gain [LG], 0.45 kg/d, vs. high gain [HG], 0.91 kg/d) on key metabolic hormones and age at puberty. After weaning at 14 ± 1 wk of age, heifers were assigned randomly to be fed HC-HG, HC-LG, HF-HG, or HF-LG ( = 12/group) beginning at 4 mo of age for 14 wk. Heifers were then switched to a common growth diet until puberty. Average daily gain was greater ( < 0.04) during the dietary treatment phase in HG heifers (0.81 ± 0.06 kg/d) than in LG heifers (0.43 ± 0.06 kg/d), and there was no diet type × rate of gain interaction. Puberty was achieved at a younger age (54.5 ± 1.8 wk) in both HG groups than in LG groups (60.2 ± 1.9 wk; < 0.04), but dietary energy source (HC vs. HF) did not influence this variable. Moreover, mean BW at puberty did not differ by diet type or rate of gain during the dietary treatment phase. Nonetheless, heifers fed HC-HG exhibited a striking increase ( < 0.0001) in serum leptin beginning at 26 ± 1 wk of age and remained elevated ( < 0.01) throughout the remainder of the experimental feeding phase compared to all other treatments. However, serum leptin in HC-HG dropped precipitously when heifers were switched to the common growth diet and did not differ from that of other groups thereafter. Overall mean concentrations of serum glucose were greater ( < 0.006) in HG heifers than in LG during the dietary treatment phase, with serum insulin also greater ( < 0.04) in HG than in LG only during weeks 20, 22, and 30. Mean serum IGF-1 was not affected by dietary type or rate of BW gain. We speculate that failure of the marked increase in serum leptin observed in HC-HG heifers during the dietary treatment phase to further accelerate puberty compared to HF-HG occurred because of its abrupt decline at the onset of the common growth phase, thus attenuating the temporal cue for activation of the reproductive neuroendocrine system.

Reproductive developmental dynamics during the early and intermediate prepuberal periods in Nelore breed (Bos indicus) calves

“…The age at puberty in Holstein calves is, on average, 250 days (8.3 mo), with approximately 30% of the calves reaching puberty as early as at 7 mo [25]. The Angus, a beef breed, reaches puberty at about 13 mo [26]. Conversely, our calves attained puberty at an average of 20.5 mo, consistently with the age previously reported by others for the Nelore breed [18].…”

The Epigenetics of Gametes and Early Embryos and Potential Long-Range Consequences in Livestock Species—Filling in the Picture With Epigenomic Analyses

“…In female offspring of malnourished fathers, oocyte meiotic competence was reduced, expression of glucose transporters in ovaries and cumulus cells was altered, and reproductive ability was compromised, as seen by lower fertilization and cleavage rates as well as embryos with delayed development (Ashworth et al, 2009). In cattle production systems, bulls are commonly placed on high-energy rations during development to result in a high rate of weight gain (Allen et al, 2017). Energy expenditure during the breeding season commonly results in weight loss in bulls, especially in bulls that have not reached their mature body weight and are still undergoing post-pubertal reproductive maturation (Cardoso et al, 2014).…”

Neuroendocrine signaling pathways and the nutritional control of puberty in heifers

“…The important effects of nutrition controlling the reproductive neuroendocrine system and pubertal progression in heifers have been well established. Previous experiments conducted by our group ( Cardoso et al ., 2014a , b; Allen et al ., 2017 ) and others ( Gasser et al ., 2006a ) have demonstrated that increasing nutrient intake during the juvenile period can markedly advance the timing of puberty in beef heifers. In studies performed by Gasser et al .…”