PS3-27. Effects of Supplementation Level and Feeding Duration on Performance of Pasture-finished Cull Cows.

Abstract This study aimed to evaluate the effect of supplementation level (SUP) of diets containing dry distillers’ bran plus solubles (DDBS; FS Fueling Sustainability, Lucas do Rio Verde, Brazil) and feeding duration (FD) on the performance of cull cows finished on pasture during the dry season. Forty-six Nellore cows [420 ± 28 kg of body weight (BW); 96 months of age) were divided into test animals (n = 36), adjustment animals (n = 6). In the beginning of the experiment, 4 cows were randomly chosen and sent to slaughterhouse to estimate the initial carcass weight. The animals were allocated to 12 paddocks (Urochloa brizantha cv. Marandu; 1.8 hectares each; 3 or 4 animals per paddock) in a randomized block design arranged in a 2 × 2 factorial scheme. The factors evaluated were: 1) supplementation level (0.5% or 1% of BW) and 2) feeding duration (42 or 84 days). Supplements (Table 1) were offered daily. The initial and final body weights of the animals at each feeding period were obtained by averaging two consecutive weighings performed at 9:00 a.m. Data were analyzed using the PROC MIXED procedure of SAS. Significance was declared when P ≤ 0.05 and a trend was considered when 0.05 < P ≤ 0.10. Animals feed for 84 days or supplemented at 1% had greater final BW (P < 0.001), final hot carcass weight (HCW; P < 0.001), final dressing percentage (P ≤ 0.063) and carcass feed gain (P ≤ 0.003) compared with animals fed for 42 days or supplemented at 0.5%, respectively. On the other hand, animals fed for 84 days showed lower average daily gain (ADG; P < 0.001) and carcass daily gain (ADGc; P < 0.001) than those fed for 42 days. Both ADG (P < 0.001) and ADGc (P < 0.001) were greater in 1% compared with 0.5%. As expected, higher supplement intake was observed at 1% compared to 0.5% (P < 0.001). Supplement intake was not affected by FD (P = 0.135). Significant interaction between SUP × FD was observed for carcass gain/hectare (P = 0.040). The highest carcass weight produced per hectare was obtained by animals supplemented at 1% for 84 days, followed by animals supplemented at 1% for 42 days, 0.5% for 84 days and 42 days, respectively. Longer feeding periods and higher supplementation levels increase final body weight, carcass weight, and carcass production per area in pasture-finished cull cows during the dry season. However, extended feeding periods reduce average daily gain. Therefore, providing higher levels of supplement may be an efficient strategy to intensify beef production and shorten the time required to finish the animals. For image description, please refer to the figure legend and surrounding text. For image description, please refer to the figure legend and surrounding text.