Improved reproductive management has allowed dairy cow pregnancies to be optimized for beef production. The objective of this sire-controlled study was to test the feedlot performance of straightbred beef calves raised on a calf ranch and to compare finishing growth performance, carcass characteristics, and mechanistic responses relative to beef × dairy crossbreds and straightbred beef cattle raised in a traditional beef cow/calf system. Tested treatment groups included straightbred beef steers and heifers reared on range (A×B; n = 14), straightbred beef steers and heifers born to Holstein (H ET; n = 15) and Jersey dams (J ET; n = 16), Angus × Holstein crossbreds (A×H; n = 15), and Angus × Jersey crossbreds (A×J; n = 16). The finishing trial began when cattle weighed 301 ± 32.0 kg and concluded after 195 ± 1.4 d. Individual intake was recorded from d 28 until shipment for slaughter. All cattle were weighed every 28 days; serum was collected from a subset of steers every 56 days. Cattle of straightbred beef genetics (A×B, H ET and J ET) and A×H were similar in final shrunk BW, dry matter intake (DMI), and carcass weight (P > 0.05 for each variable). Compared with A×J cattle, J ET were 42 days younger at slaughter with 42 kg more carcass weight (P < 0.05 for both variables). No difference was observed in longissimus muscle area between all treatments (P = 0.40). Fat thickness was greatest for straightbred beef cattle, least for A×J cattle, and intermediate for A×H cattle (P < 0.05). When adjusted for percentage of adjusted final body weight, feed efficiency was greater for straightbred beef cattle compared with beef × dairy crossbred cattle (P = 0.04). A treatment × day interaction was observed for circulating insulin-like growth factor I (IGF-I; P < 0.01); 112 d after being implanted, beef × dairy crossbred cattle had greater circulating IGF-I concentration than cattle of straightbred beef genetics (P < 0.05). Straightbred beef calves born to Jersey cows had more efficient feedlot and carcass performance than A×J crossbreds. Calves of straightbred beef genetics raised traditionally or in a calf ranch performed similarly in the feedlot.

Lactobacillus and Bacillus probiotics may serve as an alternative to antibiotics in milk replacer for pre-ruminant calves by altering gastrointestinal microflora to prevent the proliferation of harmful bacteria. However, there are limited studies evaluating their impact on calf growth and efficiency. The objective of this trial was to discover the impact of probiotic-containing milk replacer on pre-ruminating calf growth performance. A total of 44 pre-ruminant calves (50% Angus/50% Holstein, average weight 39.3 kg + 7.5 kg) were fed milk replacer with either no probiotic or 1.25x10^9 colony forming units/head/day of a probiotic blending containing Lactobacillus and two different Bacillus species (Church & Dwight Animal Nutrition (Princeton, NJ). Calves were blocked by age and randomly assigned within block to one of two treatments in a randomized complete block design. Calf was the experimental unit, with 22 calves per treatment. Calf weight and hip height was measured on d 0 and 30 to calculate average daily gain (ADG) and average growth per day. Calves were offered 1.36 kg milk replacer [15% dry matter (DM)] twice daily and up to 0.5 kg starter feed (88% DM) once daily. Refusals were recorded to calculate average daily intake and gain to feed ratio (G:F). Initial weight differed (P = 0.020) between treatments, and was therefore used as a covariate in all response criteria. Calves fed milk replacer with probiotic had greater (P < 0.05) ADG (0.53 vs. 0.42 kg/d, respectively) and G:F (0.50 vs. 0.41, respectively) than those fed the control. There was no evidence (P >0.05) that probiotic inclusion impacted hip height on d 30 or daily intake. In summary, Lactobacillus and Bacillus probiotic inclusion in milk replacer improved calf growth performance without impacting intake. Subsequent research is warranted to elucidate mode of action and evaluate impact relative to an antibiotic-containing positive control.