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Traditional heifer feeding strategies typically involve modest rates of body weight (BW) gain and include a relatively low proportion of concentrate feeds. In situations of limited forage or high feed costs, additional concentrates may be included in the diets and fed at a limited rate. High-concentrate diets can enhance the efficiency of nutrient utilization, alter characteristics of the gastrointestinal tract (GIT), and influence the composition of gain. The objective of this study was to evaluate the strategy of limit-feeding highconcentrate diets on feeding behavior, carcass characteristics, and GIT morphometrics in replacement beef heifers. Crossbred beef heifers (n = 20) began receiving either a high forage (75% forage:25% concentrate; HF, n =10) or high concentrate (25% forage:75% concentrate; HC, n =10) diet 74 ± 4 d before breeding. Heifers were inseminated with sexed male semen from a single bull. Individual intake and feeding behavior data were recorded using the Insentec Roughage Intake Control system, and heifers were weighed, and diet deliveries were adjusted every 2 wk to target a BW gain of 0.45 kg/d for both groups. Heifers were harvested at 180 d of gestation, where the viscera were removed, and weights of the full gastrointestinal tract, including the stomach complex, and small and large intestines were recorded. After removing digesta, weights of the empty gastrointestinal tract, rumen-reticulum, omasum, abomasum, small and large intestine, and mesenteric fat were recorded. Carcass characteristics were assessed 24 h after slaughter. Data were analyzed using the MIXED procedure of SAS, with heifer as the experimental unit. No differences were observed in final BW, average daily gain, or body condition score (P ≥ 0.18) between treatments (Table 1). Reflecting that HC heifers were limit-fed to a greater extent than HF heifers, therefore, dry matter intake, number of meals, visits to the feed bunk, time spent eating, and time per meal were less in HC heifers than in the HF group (P ≤ 0.001). In contrast, HC heifers had greater (P ≤ 0.001) eating rates of DM per minute, per visit and per meal compared with HF heifers. Though no differences were observed in back (P = 0.31) or rib fat (P = 0.37), HC heifers had greater (P = 0.04) marbling score and tended to have greater carcass weight (P = 0.06) and ribeye area (P = 0.07) as compared with HF heifers (Table 2). Greater (P < 0.001) full weights of GIT and stomach complex, empty weight of rumen-reticulum, weight of total digesta, and digesta as a proportion of BW (i.e., fill) were observed in HF heifers. In contrast, HC heifers had greater (P < 0.001) weights of full small intestine and mesenteric fat than HF heifers. These findings demonstrate that, despite similar rates of gain, limit-feeding high-concentrate diets can alter the composition of weight gain, favoring fat, muscle, and GIT development, potentially altering dam efficiency throughout her productive life. [ABSTRACT FROM AUTHOR]

In tropical beef cattle production systems, the impact of seasonality may be particularly challenging for young cows (primiparous or secondiparous) due to their increased nutritional requirements, encompassing maintenance, growth, gestation, and, in the case of secondiparous cows, lactation. Literature indicates that extending the duration of lactation during gestation is associated with decreased performance of progeny in their postnatal life. Therefore, implementing an early weaning approach can be an effective strategy to alleviate the nutritional demands of lactation in dams, thereby allocating more nutrients for fetal growth. This study aimed to evaluate the effect of early weaning on the feedlot performance of progeny that were in utero at the time of weaning intervention. To create experimental units, secondiparous and multiparous Nellore cows were assigned to one of two weaning strategies, where suckling calves were either; 1) early weaned 150 d (EW); or 2) conventional weaned at 240 d (CW). All calves were weaned at 150 d of lactation in 2022. Three bulls were used: Bull 1: had 13 calves with multiparous cows, had 7 calves with secondiparous cows, comprising 11 EW and 9 CW; Bull 2: had 10 calves with multiparous cows, had 6 calves with secondiparous cows, comprising 6 EW and 10 CW; and Bull 3: had 7 calves with multiparous cows, had 15 calves with secondiparous cows, comprising 11 EW and 11 CW. All cows were managed similarly after weaning, and through parturition, and weaning of subsequent calf, with resulting calves used for the current experiment. Nellore bulls (n = 57) with an initial body weight (BW) of 417.23 ± 9.12 kg and 18 mo of age were allocated to feedlot pens (equipped with Intergado equipment) and fed a common total mixed ration (80:20; concentrate:corn silage) for 97 ± 1.60 d. Bulls were distributed in a randomized complete block in a 2 × 2 factorial arrangement, considering dam weaning strategy in the previous lactation (EW and CW) and dam parity at subsequent calving (multiparous or secondiparous cows, MC and SC, respectively). Data were analyzed using PROC MIXED of SAS 9.4, with a model including the effects of dam weaning strategy, dam parity, and their interaction. Data were considered significant when P values were less than 0.05 and indicated a trend when 0.05 < P ≤ 0.10. There was an interaction between weaning strategy and cow parity, with calves born to SC-CW having reduced initial (P = 0.04) and final BW (P = 0.01) compared with all other groups (Figure 1 and 2). Steers from MC had greater dry matter intake (P = 0.003), and greater biological efficiency (P = 0.03; Table 1). Early weaning improved the final BW of steers born to secondiparous cows, suggesting it could be a strategy to enhance the performance of offspring and the reproductive performance of both secondiparous and multiparous cows. [ABSTRACT FROM AUTHOR]