Effects of bismuth subsalicylate and calcium-ammonium nitrate on ruminal in vitro fermentation of bahiagrass hay with supplemental molasses.

There is a need to increase efficiency of beef production. Decreasing losses of CH4 and improving byproduct utilization are popular strategies. Two feed additives were tested to find potential solutions. Three randomized complete block design experiments were performed using batch culture systems to evaluate the effects of bismuth subsalicylate (BSS) and calcium-ammonium nitrate (CAN) on in vitro ruminal fermentation of bahiagrass hay and supplemental molasses. The first experiment contained four treatments: (1) basal substrate; (2) basal substrate with 0.75% urea (DM basis); (3) basal substrate with 1.2% CAN and 0.38% urea (DM basis); and (4) basal substrate with 2.4% CAN (DM basis). Treatments 2, 3, and 4 were isonitrogenous. The second experiment had a 4 × 3 factorial arrangement of treatments with 4 concentrations of BSS (0.00, 0.33, 0.66, and 1.00%; DM basis) and 3 concentrations of CAN (0.0, 1.2, and 2.4%; DM basis). The third experiment had the following treatments: (1) basal substrate; (2) basal substrate with 0.05% BSS (DM basis); (3) basal substrate with 0.10% BSS (DM basis); and (4) basal substrate with 0.33% BSS (DM basis). For all experiments, basal substrate consisted of Pensacola bahiagrass hay (Paspalum notatum Flüggé; 80% substrate DM) and molasses (20% substrate DM). All data were analyzed using the MIXED procedure of SAS. In Exp. 1, in vitro organic matter (OM) digestibility (IVOMD) was linearly reduced (P < 0.001) with the inclusion of CAN, and CH4, in mmol/g OM fermented, was decreased linearly (P < 0.001). The volatile fatty acid (VFA) profile was not impacted by the inclusion of nonprotein nitrogen (NPN) or CAN (P > 0.05). In Exp. 2, except for CH4 production (P < 0.05), there were no BSS × CAN interactions. Linear reductions in total gas production (P < 0.001), IVOMD (P < 0.001), and total concentration of VFA (P = 0.007) were observed with the inclusion of BSS up to 1%. The inclusion of BSS decreased H2S production in a quadratic manner (P = 0.024). In Exp. 3, IVOMD was not impacted by the inclusion of BSS (P > 0.05); however, production of H2S was linearly decreased (P = 0.004) with the inclusion of BSS up to 0.33%. In conclusion, in vitro fermentation was negatively impacted by the inclusions of BSS, up to 1%, and CAN, up to 2.4%; however, BSS decreased production of H2S when included up to 0.33% without impeding fermentation, while CAN decreased CH4 production.

Effect of rumen-protected methionine supplementation to beef cows during the periconception period on performance of cows, calves, and subsequent offspring.

Maternal nutrition affects the development of the fetus and postnatal performance of the calf. Methionine may play a critical role in developmental programming and is likely deficient in beef cows fed low-quality forage. The objective of this study was to determine the effect of metabolizable methionine supply to lactating beef cows during the periconception period on performance of cows, calves, and subsequent offspring. This project involved two consecutive production cycles commencing at calving in which dietary treatments were fed to cows during the periconception period along with measurements on cows and initial calves in Production Cycle 1, and measurements on subsequent calves in Production Cycle 2. Brangus-Angus crossbred lactating beef cows (N = 108; age = 6.4 (2.8) year) were stratified by previous calving date and assigned to one of three supplements: (1) control, molasses plus urea at 2.72 kg/day as fed, (2) fishmeal, 2.27 kg/day molasses plus urea plus 0.33 kg/day as fed of fishmeal, and (3) methionine, 2.72 kg/day of molasses plus urea plus 9.5 g/day of 2-hydroxy-4-(methylthio)-butanoic acid. Cows were fed supplements and low-quality limpograss (Hemarthria altissima) hay while grazing dormant bahiagrass (Paspalum notatum Flüggé) pastures during the 115-day periconception period from December 2014 to April 2015 in Production Cycle 1 only. Body weight change and milk yield of cows were measured during the periconception period in Production Cycle 1. Body weight of calves was measured at birth and weaning in both production cycles. Following weaning in Production Cycle 2, eight subsequent steer calves per treatment were individually housed for a 42-day metabolism experiment. Treatment did not affect (P > 0.10) BW change of cows, but cows fed methionine tended (P = 0.09) to produce more energy-corrected milk than control and fishmeal. Treatment did not affect (P > 0.10) 205-day adjusted weaning weight of calves in either production cycle. During the metabolism experiment, subsequent calves from dams fed fishmeal and methionine gained faster (P < 0.05) and had greater (P < 0.05) gain:feed than control calves. Methionine calves tended (P = 0.06) to have greater apparent total tract NDF and ADF digestibility and lesser (P < 0.05) blood glucose concentration than control and fishmeal calves. These data indicate that maternal methionine supply during the periconception period plays an important role in programming future performance of the offspring.

The effect of follicular wave on fertility characteristics in beef cattle.

The objectives of this experiment were to determine the effects of follicular wave (first or second) on diameter of the dominant follicle, concentrations of progesterone and estradiol and the hepatic enzymes that inactivate them, thickness of the endometrium, and pregnancy rates to AI. Beef heifers ( = 101) and cows ( = 106) were randomly assigned to 1 of 2 treatments: insemination to the first follicular wave (FFW) or insemination to the second follicular wave (SFW). Estrous cycles of females were synchronized to ensure appropriate timing for the treatments. The MIXED procedure of SAS was used for analysis. A similar proportion of females in each treatment responded to presynchronization; however, females in the FFW group ovulated in response to the first injection of GnRH of the CO-Synch protocol more frequently. Only females ( = 94) that properly responded to ovulation synchronization were included in further analyses. Cows in the FFW group tended ( 0.06) to have larger ovulatory follicles 36 h post-PGF of the CO-Synch protocol compared to cows in the SFW group (14.22 ± 0.42 and 11.83 ± 0.49, respectively), whereas heifers were similar between treatment groups. Three d prior to AI, circulating concentrations of progesterone were lesser ( 0.01) in females in the FFW (3.63 ± 0.80 ng/mL) than in the SFW (7.12 ± 0.83 ng/mL), whereas concentrations of estradiol tended ( 0.08) to be greater in those in the FFW (82.72 ± 6.48 pg/mL) than in the SFW (65.55 ± 6.74 pg/mL). Concentrations of cytochrome P450 1A in the liver were lesser ( 0.01) in females in the FFW than those in the SFW (0.68 ± 0.08 vs. 0.96 ± 0.06, respectively). Endometrial thicknesses were similar between treatments but were thicker ( < 0.0001) in cows (9.73 ± 0.24 mm) than heifers (7.22 ± 0.26 mm). When considering all females or only those that were properly presynchronized, pregnancy rates were similar between treatments. However, when evaluating females that ovulated to the assigned follicular wave, there was a treatment by parity interaction ( = 0.04) with heifers in the FFW having a lesser pregnancy rate (25.9%) than heifers in the SFW (72.0%) while cows in both treatment groups were intermediate (45.4% in FFW and 50.0% in SFW). The differences in concentrations of steroids between treatment groups may affect fertility of heifers; however, additional research is necessary.

Effects of molasses and crude glycerol combined in a liquid supplement on ruminal fermentation in beef steers consuming bermudagrass hay.

Two experiments were performed to evaluate the effects of 1) increasing supplementation doses of a 50:50 (as-fed) liquid supplement of molasses and crude glycerol (M:G) on ruminal fermentation parameters and blood urea nitrogen (BUN) in beef steers consuming Tifton 85 bermudagrass ( spp.) hay and 2) different proportions of molasses and crude glycerol in a liquid supplement on in vitro fermentation and gas production kinetics. For Exp. 1, 8 ruminally cannulated, Angus-crossbred steers were used in a duplicated 4 × 4 Latin square design, had ad libitum access to Tifton 85 bermudagrass hay, and were randomly assigned to 1 of 4 treatments: 1) CTRL, no supplementation; 2) SUP1, 0.45 kg/d (as fed) of 50:50 M:G; 3) SUP3, 1.36 kg/d (as fed) of 50:50 M:G; and 4) SUP5, 2.27 kg/d (as fed) of a 50:50 M:G. For Exp. 2 in vitro batch cultures were conducted to test the same treatments from Exp. 1 and effects of different proportions of a M:G mixture (100:0, 75:25, 50:50, 25:75, and 0:100) when added to a hay substrate simulating the proportions of hay and liquid supplement used in SUP5. In Exp. 1, increasing doses of liquid supplement linearly decreased ( < 0.001) concentrations of NH-N, BUN, and acetate molar proportions, whereas propionate ( = 0.002) and butyrate ( < 0.001) molar proportions increased linearly. Treatment × time interactions were observed for ruminal pH ( < 0.001), where the greatest decrease was observed at 3 h postfeeding for animals consuming SUP5 (from 6.82 at 0 h to 6.32 at 3 h). In Exp. 2, decreases in acetate molar proportions ( < 0.001) and increases ( < 0.001) in propionate and butyrate molar proportions were also observed for either increasing doses of a 50:50 mixture or increasing proportions of glycerol in the mixture. Total VFA and in vitro organic matter digestibility were increased linearly ( < 0.001) as doses of a 50:50 mixture increased. Increasing doses of 50:50 M:G to growing beef heifers consuming bermudagrass hay caused a shift in VFA profile toward increases in propionate and decreases in acetate molar proportions. This was also confirmed in vitro, as the proportions of crude glycerol increased in a molasses:crude glycerol mix. Thus, molasses and crude glycerol combined seem to be useful to enhance performance in growing cattle consuming forage-based diets.