Effects of live yeast (Saccharomyces cerevisiae) in steam-flaked corn-based diets fed to natural-program beef cattle on growth performance, total tract apparent digestibility, carcass characteristics, and feeding behavior were evaluated in a randomized block design experiment. Steers (n = 144; 341 ± 7.03 kg) were blocked by initial BW and assigned randomly to 1 of the 3 treatments (n = 12 pens per treatment with 4 steers per pen). Treatments included the following: 1) control (CTL; no yeast); 2) low yeast (LY; 1.5 g/animal daily [3 × 1010 CFU]); and 3) high yeast (HY; 3.0 g/animal daily [6 × 1010 CFU]). Technologies such as implants, ionophores, and antibiotics were not used, and the steam-flaked corn-based finishing diets were fed to provide ad libitum access to feed. Yeast was included in a cottonseed meal-based premix as 1% of the dietary DM. Spot fecal samples (twice daily for 5 consecutive days) and diets were composited by pen and analyzed for acid insoluble ash to estimate apparent total tract digestibility of nutrients. Cattle were slaughtered on days 183 (4 blocks) and 204 (8 blocks). Dry matter intake (P ≥ 0.29), ADG (P ≥ 0.17), and G:F (P ≥ 0.33) did not differ among treatments. The percentage of Premium Choice (P < 0.01) carcasses increased linearly with increasing yeast inclusion in the diet. A quadratic response was observed for total tract apparent digestibility, in which steers fed LY had greater digestibility (P < 0.01) of DM by 5.4%, OM by 4.8%, NDF by 15.2%, ADF by 20.2%, CP by 6.2%, and ether extract (EE) by 2.5% compared with steers fed CTL. Feeding behavior was not affected (P = 0.28) by treatments. Live yeast improved digestibility of DM, OM, CP, EE, and fiber, without changing feeding behavior and growth performance of natural-program steers fed steam-flaked corn-based finishing diets.

Genetic and reproductive advancements in the dairy industry, volatile milk markets, and beef packer restrictions on dairy carcasses have increased the popularity of crossbreeding beef breed sires with dairy cows in the U.S. This observational study aimed to understand performance in dairy cows bred to beef sires and feedlot and carcass performance of crossbred beef × dairy calves. For dairy cow performance, archived records from 2 dairies representing 2 successive lactations were evaluated in paired cows (Dairy A: n=72/group; Dairy B: n=456/group) representing either: 1) All Dairy, where previous sire type of conception was Holstein for both lactations, or 2) Beef on Dairy, where previous sire type of conception was Holstein for the preceding lactation and a beef breed for the subsequent lactation. For feedlot performance, closeout data from paired pens (n=26/cattle type) of beef and beef × dairy calves were evaluated and numerically compared to pens (n=5) of Holstein steers. For carcass analysis, individual data were compared between carcasses from conventional beef (n=966), beef × dairy (n=518), and Holstein (n=935) steers. Cow performance was minimally impacted by sire type of previous conception. Cows conceived to beef sires exhibited a 2 to 3 d greater (P&lt;0.01) gestation time than cows conceived to Holstein sires. Feedlot growth performance of beef × dairy pens was intermediate to beef pens (P&lt;0.01) and Holstein steers. Beef × dairy pens had lesser (P≤0.02) feed conversion and dressing percent than beef pens. Both feedlot closeouts and carcass data showed that beef × dairy calves produced a greater (P&lt;0.05) percent Yield Grade 2 carcasses and a lower (P&lt;0.05) percent Yield Grade 4 carcasses than beef calves. Beef × dairy carcasses exhibited less (P&lt;0.05) fat than beef steers and larger (P&lt;0.05) ribeyes than Holsteins. Carcass cutability advantages for beef × dairy did not come at a sacrifice to carcass quality, as beef × dairy steers generated a greater (P&lt;0.05) percent Upper 2/3 Choice and Low Choice carcasses and a lower (P&lt;0.05) percent Select carcasses than beef steers. Thus, the U.S. beef and dairy industries alike should encourage production of terminal beef × dairy calves rather than continued inefficient production of Holstein steers. Efficiency savings in producing beef × dairy calves make it a more environmentally conscious and sustainable production practice than production of traditional dairy calves for the beef supply chain.

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Since the early 1900s, scientists have been comparing phenotypic characteristics of purebred and crossbred dairy cows in an attempt to determine the advantages of heterosis. However, the benefit of heterosis on the immune system has not been investigated during the transition period in lactating dairy cows. Innate immunity during the transition period (three weeks pre- to three weeks postpartum) plays a critical role on the postparturient health of dairy cows. The objectives of this study were to compare dry matter intake (DMI), metabolite concentration, innate immunity, and postpartum health of purebred Holstein (HO) and Montbeliarde-sired crossbred (MS) cows.