Impact of supplemental protein source offered to primiparous heifers during gestation on II. Progeny performance and carcass characteristics

Abstract

A 3-yr study using primiparous crossbred beef heifers (n = 114) was conducted to determine the effects of protein supplement during late gestation on progeny performance and carcass characteristics. Pregnant heifers were stratified by heifer development system, initial BW, and AI service sire and placed in an individual feeding system. Heifers were offered meadow hay (8 to 11% CP) from early November to mid-February and provided no supplement (CON; n = 37), 0.83 kg/d (DM basis) of a dried distillers grains with solubles-based supplement (HI; n = 39), or 0.83 kg/d (DM basis) of a dried corn gluten feed-based supplement (LO; n = 38). Supplements were designed to be isonitrogenous (28% CP) and isocaloric but to differ in RUP with HI (59% RUP) having greater levels of RUP than LO (34% RUP). After the individual feeding period, heifers were placed in a drylot for calving. All heifers were bred using a fixed-timed AI protocol and pairs were moved to a commercial ranch in the Nebraska Sandhills for summer grazing. Calf weaning BW did not differ (P = 0.14) based on maternal diet. However, feedlot entry BW was greater (P = 0.03) for HI compared with CON calves. Average daily gain during the initial feedlot phase tended (P = 0.10) to be greatest for calves born to CON dams and lowest for calves born to LO dams. However, overall ADG was similar (P = 0.50) for the entire feedlot period. Residual feed intake during the reimplant and total feeding period was improved in calves born to supplemented dams in yr 2 and 3 compared with calves born to CON dams. There was no difference in final BW among treatments (P = 0.71). Hot carcass weight was similar (P = 0.72) among treatments; however, steers had greater (P < 0.01) HCW than heifers. Furthermore, percent empty body fat and 12th rib fat thickness were lowest (P = 0.05 and P = 0.04) for calves born to LO dams. Tenderness measured by Warner-Bratzler shear force was increased (P = 0.03) in longissimus samples from calves from CON dams compared to calves from LO dams. Similarly, crude fat levels tended to be greater (P = 0.07) for calves from CON dams compared with calves from LO dams. Based on these data, providing RUP supplements, similar to those used in this study, to primiparous heifers in late gestation consuming ad libitum grass hay resulted in increased initial feedlot BW for HI compared to CON calves, improved feed efficiency, and altered carcass characteristics in calves born to supplemented compared with CON dams.

Impact of supplemental protein source offered to primiparous heifers during gestation on I. Average daily gain, feed intake, calf birth body weight, and rebreeding in pregnant beef heifers

“…Differences in birth weight due to calf sex is likely the cause of increased calving difficulty in those heifers giving birth to bull compared with heifer calves and has been noted previously in the literature (Burfening et al, 1978;Berger et al, 1992;Eriksson et al, 2004). Subsequent postnatal calf performance through slaughter is reported elsewhere (Summers et al, 2015).…”

Increased dietary protein in the second trimester of gestation increases live weight gain and carcass composition in weaner calves to 6 months of age

“…Such perturbations to placental development may reduce foetal growth due to decreased nutrient transport via the placenta (Sullivan et al ., 2009c) generating a decrease in birth weight (Perry et al ., 1999; Micke et al ., 2010c), or alternatively dichotomous placental development (as in the LH group) may be attendant to increased birth weight and associated dystocia.…”

“…It has previously been reported that gestational dietary regimens effectively alter placental signalling hormones (Sullivan et al ., 2009c; Summers et al ., 2015). These may act to signal foetal skeletal muscle IGF messenger RNA (mRNA) expression and fibre development during the first two trimesters of gestation as previously shown in foetal skeletal sheep muscle where nutritional restriction increased IGF-2 mRNA expression (Brameld et al ., 2000) and increased IGF receptor activity (Symonds et al ., 2012).…”

CELL BIOLOGY SYMPOSIUM: METABOLIC RESPONSES TO STRESS: FROM ANIMAL TO CELL: Poor maternal nutrition during gestation: effects on offspring whole-body and tissue-specific metabolism in livestock species1,2

“…However, there are limited data available assessing the effects of poor maternal diet on offspring RFI. Offspring of primiparous beef heifers supplemented with rumen-undegraded protein during late gestation demonstrated decreased RFI (increased efficiency) compared with offspring of unsupplemented dams during the feedlot period (Summers et al, 2015). However, Meyer et al (2014) found no differences in RFI, DMI, G:F, or ADG during finishing in steers or heifers born to cows that were nutrient restricted (70% of control) during early gestation and midgestation.…”