The effects of dietary energy and recombinant bovine somatotropin (bST) on pattern of LH release, follicular development, and onset of puberty were studied in 40 Angus heifers. At 7 mo of age, heifers were assigned to a 2 x 2 factorial experiment; the main effects were dietary energy (high [HDE]: 14.15 Mcal of ME/d or moderate [MDE]: 10.84 Mcal of ME/d) and somatotropin (bST; 350 mg every 2 wk ...

Our objective was to determine if prolonged exposure to various durations of light (i.e., photoperiod) would affect serum IGF-I concentrations in heifers. Thus, 16 Holstein heifers, 2 to 4 mo of age, were exposed during a 5-wk pretreatment period to 12 h of cool-white fluorescent light (L) at an intensity of 1200 lux and 12 h of dark (D). At 5 wk, photoperiods were adjusted to 24 L: 0 D (24 L),...

The objective of this study was to determine the influence of supplemental feeding of perennial peanut hay (Arachis glabrata Benth.) on growth performance and age at puberty in growing beef cattle heifers. Over a two-year (2010 and 2011) period, 120 heifers were randomly allocated to pens and assigned to one of three supplement treatments: 80% corn and 20% soybean meal supplement (CSBM), perenn...

The objective of the experiment was to examine the necessity of adding a GnRH injection to a 14-d controlled internal drug release (CIDR)-based protocol for synchronization of estrus in beef heifers that were prepubertal or estrous-cycling at the initiation of treatment. The hypothesis tested was that the addition of GnRH in a CIDR-based estrus synchronization protocol would increase the synchr...

Experiments were conducted to compare clostridial antibody response of beef heifers that do and do not develop injection-site lesions, evaluate long-term antibody response of a single- and multiple-dose toxoid, and evaluate the ability of a clostridial toxoid to elicit an active antibody response in newborn calves. In Exp. 1, 37 weaned heifers were vaccinated (d 0) with a clostridial vaccine (A...

Central nervous system peptide and amino acid modulation of luteinizing hormone and prolactin secretion in the pig. Influence of opioids on LH secretion in gilts during the estrous cycle. D. Schams: Reg~lation of bovine intra-luteal function by peptide hormones. We have utilized active immunization against growth hormone releasing factor (GRF) to investigate relationships among somatotropin (ST...

The objective of this study was to determine how duration of time that cattle are fed a high-grain diet affects feed sorting, both before and after an episode of acute ruminal acidosis. Sixteen Angus heifers (261 ± 6.1 kg; BW ± SEM) were assigned to 1 of 4 blocks and fed a backgrounding (BG) diet (60% forage, DM basis). Within block, heifers were randomly assigned to 1 of 2 treatments differing...

The objective of this study was to evaluate the effects of acclimation to handling on growth, plasma concentrations of progesterone (P4) and cortisol, temperament, and reproductive performance of Brahman-crossbred heifers. Over 2 consecutive years, 37 Braford and 43 Brahman x Angus heifers were initially evaluated, within 30 d after weaning, for BW and puberty status via transrectal ultrasonogr...

AIMS: To investigate factors associated with pregnancy rate in a number of herds of contract rearing replacement dairy heifers. These factors included the average daily gain of a heifer mob, the average bodyweight of the mob at the start of grazing, the number of heifers in the mob, the length of the grazing period, the breed of heifers, the grazing season and the region from where the heifers ...

Six hundred sixty-five crossbred beef heifers initially weighing 225 kg were used in a completely randomized design to measure plasma glucose, lactate, and urea N concentrations at time of initial processing, determine the incidence of apparent bovine respiratory disease (BRD) in receiving cattle, and evaluate the effect of apparent BRD on subsequent cattle growth and carcass characteristics. H...