Growth and reproductive performance of 14- to 15-month-old Hereford heifers

Abstract

-Aiming at breeding heifers with 14-15 months of age, 100 Hereford calves were subjected to different feeding systems. Heifers grazed on a natural pasture in early winter, fed or not a supplement (14% crude protein; 72% total digestible nutrients), were transferred to a ryegrass pasture for 73 days, and then returned to a natural pasture for 15 days until the beginning of the breeding season. During the last 15 days on ryegrass pasture and the 15 days of the return to the natural pasture, half of the heifers of the two previous systems were offered the supplement, thereby establishing four feeding treatments. Heifers supplemented during the second period, independently of supplementation during the first grazing period, presented higher average daily gain and greater backfat values than the non-supplemented heifers. The breeding season extended for 75 days. At the start of the breeding season (November 18), heifers supplemented during both periods presented higher body condition score and body weight. The highest percentage of puberty was determined in heifers supplemented in the early winter. Heifers supplemented during both periods presented the highest pregnancy rate. Pregnant heifers presented higher average daily gain when fed the supplement during the second period, as well as higher relative pelvic area, body weight, and body condition score at the start and end of the breeding season. To an expressive pregnancy in 14-to 15-month-old heifers, higher weaning weights and pasture allowance are required to get a better answer to supplements offered.

Average daily gain rates determine eye muscle area and rump fat depth of beef heifers

“…The deposition of rump fat depth before breeding season translates into body reserves and may be related to the anticipation of puberty (Randel and Welsh 2013). Heifers who have a higher ADG and higher BW before the breeding season, are heifers that can conceive at 14-15 months of age, as reported by Landarin et al (2016). Therefore, as the rate of ADG can be controlled through selective management practices, age at puberty can be predicted (Arije and Wiltbank 1974).…”

“…In beef heifers, these factors are affected by the rate of average daily gain (ADG) post-weaning, among other factors (Greer et al 1983;Bagley 1993;Barcellos et al 2014). There are several reports in the international literature on the development of replacement beef heifers (Lancaster et al 2009;Lardner et al 2014;Moriel et al 2014;Landarin et al 2016). However, there are few studies evaluating the impact of ADG on body composition traits during heifer development.…”

Influence of age and weight of Girolando heifers on uterine and ovarian development

“…The average age at puberty for Zebu breeds may vary according to the intensity of the production system and the appropriate nutritional management (Nogueira, 2004), as well as the weight that these animals present at their first ovulation. Landarin et al (2016) concluded from the results of several authors that the weight at puberty of F1 animals from the cross between Holstein and Zebu cattle ranges from 300 to 340 kg, more specifically 307 kg for F1 crossbred Holstein × Gir heifers. In a study by Bergfeld et al (1994), heifers that were fed to achieve an average daily gain of 0.9 kg were 12.4 months old at puberty, while their contemporaries that received a diet to reach an average of 0.3 kg per day reached puberty at 14.5 months old.…”