Heifer Body Weight Gain and Reproductive Achievement in Response to Protein and Energy Supplementation While Grazing Dormant Range Forage

Abstract

Heifers grazing winter range require supplemental nutrients to complement dormant forage to achieve optimal growth and performance. A study was conducted to evaluate nutritional environment and effect of different supplementation strategies for developing heifers grazing dormant winter range. Eighty-four Angus crossbred heifers were stratified by body weight at weaning, allocated to one of six replicated pastures, and randomly assigned one of three supplemental treatments: 1) 908 g/d of a control supplement providing 340 g·hd −1 ·d −1 of CP with 130 g of rumen undegradable protein (RUP) and 614 MJ of ME (LRUP); 2) 908 g/d of a RUP supplement providing 340 g·hd −1 ·d −1 of CP with 170 g of RUP and 567 MJ of ME (HRUP); or 3) 1814 g/d of a protein and energy supplement providing 340 g·hd −1 ·d −1 of CP with 120 g of RUP + 100 g of propionate salt (NutroCal ™ , Kemin Industries, Inc.) and 1222 MJ of ME (LRUP + E). Body weights were taken in November, with monthly 12 h shrunk BW from January thru April, and again in September (at time of pregnancy diagnosis). Heifer average daily gain was similar throughout the developmental period except from d125 to d159 where LRUP + E supplemented heifers had greater gains (P < 0.01) than LRUP and HRUP supplemented heifers (0.33, 0.04, and 0.14 ± 0.05 kg/d, respectively). LRUP + E heifers had a greater percentage (P = 0.04) of heifers pubertal at time of artificial insemination compared to LRUP and HRUP heifers (57, 29, and 30, respectively). However, no differences were * Corresponding author. R. C. Waterman et al. 1297 detected in overall pregnancy rates (P = 0.40). This study indicated that feeding more supplemental energy (i.e., propionate salt, ground milo and corn) allowed lightweight heifers to achieve a greater rate of gain at a key period during development and achieved comparable reproductive success to heifers only receiving supplemental protein.

Effects of reduced in utero and post-weaning nutrition on milk yield and composition in primiparous beef cows

“…However, Endecott et al (2013) suggests changes in mature BW have occurred over the decades and the recommendation for heifer target BW before breeding of 60% to 65% of mature weight may be different today than when first reported. Recent studies have shown that developing heifers to a lighter targeted BW of 50% to 57% allowed for reductions in heifer development costs and acceptable reproductive performance (Roberts et al, 2009a;Mulliniks et al, 2013;Waterman et al, 2014). The question then arises; how is first parity lactation impacted by this change in growth curve of heifers developed at BW <60% of mature BW?…”

Effects of rumen-undegradable protein on intake, performance, and mammary gland development in prepubertal and pubertal dairy heifers

“…In addition, RUP supplementation is recognized as a glucogenic source and responsible for increasing serum insulin levels (Table 6; Wiley et al, 1991;Waterman et al, 2006). Thus, the best performance for animals fed 51% of RUP may also be linked to a greater insulin sensitivity caused by this level of RUP inclusion (Waterman et al, 2014).…”