PSXII-26 The influence of protein supplementation in beef cows during early lactation on growth performance, carcass characteristic and meat quality of progeny

Abstract At 11 ± 4 d of lactation, 30 multiparous Angus cows [body weight (BW) = 476 ± 17 kg, body condition score (BCS) = 4.5 ± 0.3) were stratified by BW and allotted in 6 pens (5 cows/pen). During 75 d of experiment, all pens received ad libitum low quality hay (Panicum italicum; 54.7% TDN, 6.1% CP DM basis) and were randomly assigned to one of two treatments: 1) PS; cows received ad libitum 30% CP supplement including an intake limiter component (Controlmix, Nutralmix SRL, Argentina), or 2) NS; cows were not supplemented. After the experimental period, dams and their calves (PS: 7 males and 8 females; NS: 8 males and 7 females) were managed on improved pastures as a single group until weaning at 213 d of age. After weaning, heifer and steer calves were reared on improved pastures until 448 d of age, then placed into a feedlot with a finishing diet during 73 d until slaughter. Pens were considered the experimental unit and data were analyzed using the PROC MIXED of SAS, considering treatment and sex as a fixed effects and pen as a random effect. Overage dry matter intake (DMI) of hay was not affected by treatments (P > 0.10), and DMI of supplement in PS cows was 4.4 kgּ cow-1ּ d-1. Milk production was greater in PS than NS cows (PS: 5.3, NS: 3.6 kgּ cow-1ּ d-1; P < 0.01). Progeny from PS cows increased BW at weaning (PS: 180, NS: 141 kg; P < 0.01), BW at initial feedlot phase (PS: 300, NS: 252 kg; P = 0.01) and final BW (PS: 415, NS: 354 kg; P = 0.01). After slaughter, progeny from PS cows tended to have increased dressing percentage (PS: 59.0, NS: 58.1%; P = 0.09), had an increased hot carcass weight (PS: 227, NS: 191 kg; P < 0.01), and increased Longissimus muscle (LM) area (PS: 68.5, NS: 60.1 cm2; P = 0.02), while rib fat thickness was not affected by treatments (PS: 7.8, NS: 7.6 mm; P = 0.68). There was no effect of protein supplementation on color (L*, a*, b*) and pH of LM at 24 h postmortem (P > 0.10). In addition, moisture, ether extract and shear force of LM after 4 d of aging were similar between treatments (P > 0.10). There was no treatment × sex interaction for any variables (P > 0.10). This study showed that protein supplementation during early lactation improved growth performance and carcass quality, but did not result in enhanced meat quality of progeny.