Effect of undegradable intake protein supplementation on intake, digestion, microbial efficiency, in situ disappearance, and plasma hormones and metabolites in steers fed low-quality grass hay

Effect of protein and glucogenic precursor supplementation on forage digestibility, serum metabolites, energy utilization, and rumen parameters in sheep

Supplementation of glucogenic precursors in roughage diets may increase production responses due to improved efficiencies of nutrient utilization. Therefore, the objective of this study was to determine the effect of source of supplemental glucogenic potential (GP) on forage digestibility, serum metabolites, energy utilization, and rumen parameters of growing wethers consuming a roughage diet (8.8% crude protein, 71.4% ash-free neutral detergent fiber). Crossbred wethers (49.1 ± 4.7 kg initial BW; n = 16) were utilized in a 4 × 4 replicated Latin Square design with four periods of 21 d. Supplements were designed to supplement increasing amount of GP: 1) no supplementation (CON; 0 g), 2) 40 g of calcium propionate (CAP; 30 g of GP), 3) 70 g of blood meal + 100 g of feather meal (BF; 40 g of GP), or 4) combination of CAP and BF (COMBO; 70 g of GP). Total fecal and urine collection was conducted from days 13–17 to calculate digestibility estimates and urinary losses. An acetate tolerance test was administered on day 17 to determine the effect of GP on acetate clearance. Blood samples were collected on day 19 and were analyzed for serum concentrations of glucose, urea N (SUN), non-esterified fatty acids, and amino acids. Rumen fluid was collected on day 21 to determine supplementation effects on ruminal volatile fatty acid (VFA) and ammonia concentrations. Wethers receiving BF and COMBO supplementation had greatest (P ≤ 0.01) DM and OM total tract digestibility. Supplementation did not affect (P ≥ 0.37) NDF digestibility or digestible energy. Urinary nitrogen excretion was greatest (P = 0.02) for BF and COMBO. Circulating serum essential amino acid concentration was increased (P < 0.01) in BF and COMBO compared to CAP and CON. In addition, BF and COMBO had increased (P < 0.01) SUN concentrations compared to CAP and CON. Acetate half-life was not affected (P = 0.39) by supplementation strategy. However, area under the curve (AUC) for acetate was decreased (P = 0.04) with supplementation of BF and COMBO compared to CON-fed wethers. Ruminal propionate concentration was increased (P ≤ 0.01) for wethers fed CAP and COMBO supplementation, which resulted in decreased (P ≤ 0.01) A:P ratio. Overall, these results indicate that the increased propionate supply by providing propionate salts did not result in a protein sparing impact or increased N retention.

Effect of increased inclusion of dried distillers grain supplement on adaptation, intake, digestibility, and rumen parameters in steers consuming bermudagrass round bale silage

Eight ruminally cannulated beef steers were used to evaluate forage intake and physiological response during adaptation to a diet consisting of bermudagrass round bale silage (RBS) and dried distillers grains (DDG) and in a second experiment the effect of level of DDG supplementation on RBS forage intake, digestibility, and rumen parameters. The adaptation experiment was designed to simulate a 14-d step-up process. Initially steers received ad libitum RBS, on d 4 steers were offered 1.13 kg of DDG daily and every 4 d daily DDG offered was increased by 1.13 kg. Blood and rumen fluid samples were collected before feeding (0 h) and 6, 12, 24 (before feeding), and 36 h after every diet change. The digestibility experiment was conducted as an 8 × 4 Latin square with four periods. Treatments included RBS only and DDG supplement levels of 0.33%, 0.66%, and 1.0% of body weight (RBS + 0.33, +0.66, and 1.0, respectively). Collection periods consisted of 21 d to determine dry matter intake [DMI], digestibility, and collect rumen fluid samples. During adaptation, level of DDG did not (P = 0.42) affect RBS DMI. Mean ruminal pH was greater (P < 0.05) for RBS only compared with diets with DDG. When steers were offered 3.39 or 4.52 kg/d of DDG rumen NH₃-N concentration was greater (P ≤ 0.05) compared with other levels of DDG or RBS alone. Mean nonesterified fatty acid and plasma urea N concentrations varied among levels of DDG offered. In the digestibility experiment forage DMI, total DMI, and total tract apparent digestibility exhibited a quadratic (P ≤ 0.05) response to level of DDG offered. Mean ruminal pH responded in a quadratic manner (P = 0.03) and was greater for RBS only compared with RBS plus DDG at any level. Mean ruminal NH₃-N concentration tended (P = 0.07) to respond in a cubic manner as DDG amount offered increased. Physiological responses during adaptation to DDG over 14 d resembled responses previously observed after long-term DDG supplementation. Offering DDG up to 1% of body weight did depress forage DMI and ruminal pH but increased total DMI, diet digestibility, and ruminal NH₃-N concentration.

Effects of crude protein and undegradable intake protein on growth performance, nutrient utilization, and rumen fermentation in growing Thai-indigenous beef cattle

The objective of this study was to investigate growth performance, nutrients apparent digestibility, nitrogen utilization, rumen fermentation, and rumen microorganism of growing Thai-indigenous beef cattle receiving different levels of crude protein (CP) and undegradable intake protein (UIP) diets. Eighteen healthy growing Thai-indigenous beef cattle were used in a 2 × 3 factorial randomized complete block design (RCBD). There were six treatments: two levels of CP (10% and 12% of dry matter (DM)) and three levels of UIP (15%, 25%, and 35% of CP). The results indicated that dry matter intake (DMI) and average daily gain (ADG) increased linearly (P < 0.01) with increasing UIP level. The apparent digestibility of DM, organic matter (OM), acid detergent fiber (ADF), and neutral detergent fiber (NDF); rumen fermentation parameters; microbes counts; and microbial nitrogen synthesis (MNS) were unaffected (P > 0.05) by CP and UIP levels. The nitrogen (N) intake and N retained increased linearly (P < 0.01) with increasing UIP level. Specifically, the metabolizable protein (MP) requirement of 1 g/kg BW^0.75 gain was 0.34 g MP/kg BW^0.75; the 10% dietary CP of DM was able to meet animals' normal nutrition requirements and 6.5% DIP of DM can provide adequate N source for the requirement of rumen microbe growth in. Collectively, it was indicated that the supplemental level of 10% CP and the ratio of UIP to DIP was 35:65 in diets shown the best growth performance for growing Thai-indigenous beef cattle under the conditions in the current study.

Effects of rumen-protected arginine supplementation and arginine-HCl injection on site and extent of digestion and small intestinal amino acid disappearance in forage-fed steers

Four ruminally and intestinally cannulated steers were used in a 4 × 4 Latin square to evaluate effects of rumen-protected Arg supplementation or intravenous Arg injection on small intestinal delivery of AA, site and extent of digestion, and ruminal fermentation. Steers were fed grass hay (7.2% CP, 67.6% NDF, 0.29% Arg) for ad libitum intake with no additional Arg (CON), 54-mg L-Arg/kg BW injected intravenously (Arg-INJ), 180-mg rumen-protected L-Arg/kg BW daily (Arg-RP180), or 360-mg rumen-protected L-Arg/kg BW daily (Arg-RP360). Half of each treatment dose was administered twice daily. Each period had a 7-d washout of hay only followed by a 14-d treatment and collection period. Ruminal disappearance (%) of Arg was greater (P < 0.001) for both Arg-RP treatments than CON and Arg-INJ, although the amount of Arg disappearing was greatest in Arg-RP360, followed by Arg-RP180, and least in CON and Arg-INJ (P < 0.001). Duodenal flow and small intestinal disappearance (g/d) of Arg was greatest in Arg-RP360, followed by Arg-RP180, and least in CON and Arg-INJ (P < 0.004). Ileal flow of Arg was greatest in Arg-RP360, intermediate in Arg-RP180, and least in CON (P = 0.01) because the proportional small intestinal disappearance of Arg was not different (P = 0.96). Steers fed Arg-RP360 had greater (P = 0.01) ileal flow of Orn and tended to have greater (P = 0.09) ileal flow of Glu than all other treatments. There were no differences in hay or total DMI, microbial efficiency, or OM, NDF, or ADF digestibility (P ≥ 0.10). Total N intake and duodenal N flow were greater in Arg-RP360 than all other treatments (P ≤ 0.02). Total tract N digestibility was greatest in Arg-RP360, followed by Arg-RP180, and least in CON and Arg-INJ (P = 0.003). Ruminal ammonia was greater (P = 0.004) in Arg-RP360 compared with CON and Arg-INJ and greater (P = 0.06) in Arg-RP180 than CON. There was no effect of treatment (P ≥ 0.37) on total VFA, acetate, propionate, or butyrate concentrations. Results indicate that feeding rumen-protected Arg increases small intestinal Arg flow with minimal effects on ruminal fermentation and total tract digestibility of OM and fiber.

In vivo ruminal degradation characteristics and apparent digestibility of low-quality prairie hay for steers consuming monensin and Optimase

Seven ruminally cannulated crossbred steers (BW = 720 ± 62 kg) were used in a randomized crossover design (4 periods, each 18 d) to evaluate in vivo rumen characteristics and apparent digestibility of steers consuming low-quality prairie hay and 1 of 4 isonitrogenous protein supplements. Treatments included 1) 40% CP (DM basis) cottonseed meal and wheat middlings-based supplement (Control), 2) a cottonseed meal and wheat middlings-based supplement with slow-release urea and a fibrolytic feed enzyme (Optimase; Alltech, Inc., Nicholasville, KY) designed to replace 30% of plant-based CP provided in the Control (OPT), 3) the Control plus 0.40 mg∙kg BW∙d monensin (Rumensin 90; Elanco Animal Health, Greenfield, IN; MON), and 4) the OPT plus 0.40 mg∙kg BW∙d monensin (COMBO). Steers were allowed ad libitum access to prairie hay (5.0% CP and 76% NDF) and were provided each respective supplement at 0800 h daily at a rate of 1.0 g/kg of BW. Steers were adapted to diets for 10 d before sample collection. Beginning on d 11, DMI was measured and samples were collected to determine apparent digestibility. On d 15 of the 18-d period, rumen fluid was collected 10 times over a 24-h period. Forage DMI was greater ( ≤ 0.02) for steers consuming the OPT compared with steers consuming the MON or COMBO, although forage DMI was not different ( = 0.10) among steers consuming the Control compared with steers consuming the OPT, MON, or COMBO. Steers fed the MON and COMBO had lower ( ≤ 0.05) passage rate compared with steers fed the Control and the OPT. The MON-fed steers had lower ( = 0.01) ruminal pH and increased ( = 0.03) propionate as a percentage of total VFA production. A time × treatment ( = 0.01) interaction was observed for ruminal NH-N due to a rapid (0 to 1 h after feeding) increase followed by a quick (1 to 4 h after feeding) decline in NH-N by steers consuming the OPT and COMBO that was not observed for steers consuming all other treatments. Apparent digestibility of DM ( = 0.01) and NDF ( = 0.03) were improved for steers fed the COMBO supplement compared with steers consuming all other experimental supplements. This work suggests that the OPT may be an effective replacement for a portion of supplemental degradable intake protein in low-quality forage. Further research is necessary to determine if the combination of monensin and the Optimase consistently improves low-quality forage utilization.

Effects of protein supplementation frequency on physiological responses associated with reproduction in beef cows

The objective of this experiment was to determine if frequency of protein supplementation impacts physiological responses associated with reproduction in beef cows. Fourteen nonpregnant, nonlactating beef cows were ranked by age and BW and allocated to 3 groups. Groups were assigned to a 3 × 3 Latin square design, containing 3 periods of 21 d and the following treatments: 1) soybean meal supplementation daily (D), 2) soybean meal supplementation 3 times/week (3WK), and 3) soybean meal supplementation once/week (1WK). Within each period, cows were assigned to an estrus synchronization protocol: 100 μg of GnRH + controlled internal drug release device (CIDR) containing 1.38 g of progesterone (P4) on d 1, 25 mg of PGF2α on d 8, and CIDR removal + 100 μg of GnRH on d 11. Grass-seed straw was offered for ad libitum consumption. Soybean meal was individually supplemented at a daily rate of 1 kg/cow (as-fed basis). Moreover, 3WK was supplemented on d 0, 2, 4, 7, 9, 11, 14, 16, and 18 whereas 1WK was supplemented on d 4, 11, and 18. Blood samples were collected from 0 (before) to 72 h after supplementation on d 11 and 18 and analyzed for plasma urea-N (PUN). Samples collected from 0 to 12 h were also analyzed for plasma glucose, insulin, and P4 (d 18 only). Uterine flushing fluid was collected concurrently with blood sampling at 28 h for pH evaluation. Liver biopsies were performed concurrently with blood sampling at 0, 4, and 28 h and analyzed for mRNA expression of carbamoyl phosphate synthetase I (CPS-I; h 28) and CYP2C19 and CYP3A4 (h 0 and 4 on d 18). Plasma urea-N concentrations were greater (P < 0.01) for 1WK vs. 3WK from 20 to 72 h and greater (P < 0.01) for 1WK vs. D from 16 to 48 h and at 72 h after supplementation (treatment × hour interaction, P < 0.01). Moreover, PUN concentrations peaked at 28 h after supplementation for 3WK and 1WK (P < 0.01) and were greater (P < 0.01) at this time for 1WK vs. 3WK and D and for 3WK vs. D. Expression of CPS-I was greater (P < 0.01) for 1WK vs. D and 3WK. Uterine flushing pH tended (P ≤ 0.10) to be greater for 1WK vs. 3WK and D. No treatment effects were detected (P ≥ 0.15) on expression of CYP2C19 and CYP3A4, plasma glucose, and P4 concentrations, whereas plasma insulin concentrations were greater (P ≤ 0.03) in D and 3WK vs. 1WK. Hence, decreasing frequency of protein supplementation did not reduce uterine flushing pH or plasma P4 concentrations, which are known to impact reproduction in beef cows.

Beef Species Symposium: an assessment of the 1996 Beef NRC: metabolizable protein supply and demand and effectiveness of model performance prediction of beef females within extensive grazing systems

Interannual variation of forage quantity and quality driven by precipitation events influence beef livestock production systems within the Southern and Northern Plains and Pacific West, which combined represent 60% (approximately 17.5 million) of the total beef cows in the United States. The beef cattle requirements published by the NRC are an important tool and excellent resource for both professionals and producers to use when implementing feeding practices and nutritional programs within the various production systems. The objectives of this paper include evaluation of the 1996 Beef NRC model in terms of effectiveness in predicting extensive range beef cow performance within arid and semiarid environments using available data sets, identifying model inefficiencies that could be refined to improve the precision of predicting protein supply and demand for range beef cows, and last, providing recommendations for future areas of research. An important addition to the current Beef NRC model would be to allow users to provide region-specific forage characteristics and the ability to describe supplement composition, amount, and delivery frequency. Beef NRC models would then need to be modified to account for the N recycling that occurs throughout a supplementation interval and the impact that this would have on microbial efficiency and microbial protein supply. The Beef NRC should also consider the role of ruminal and postruminal supply and demand of specific limiting AA. Additional considerations should include the partitioning effects of nitrogenous compounds under different physiological production stages (e.g., lactation, pregnancy, and periods of BW loss). The intent of information provided is to aid revision of the Beef NRC by providing supporting material for changes and identifying gaps in existing scientific literature where future research is needed to enhance the predictive precision and application of the Beef NRC models.

Effect of dried distillers' grain, soybean meal and grain or canola meal and grain-based supplements on forage intake and digestibility

Van De Kerckhove, A. Y., Lardner, H. A., Yu, P., McKinnon J. J. and Walburger, K. 2011. Effect of dried distillers' grain, soybean meal and grain or canola meal and grain-based supplements on forage intake and digestibility. Can. J. Anim. Sci. 91: 123–132. Four ruminally cannulated beef heifers (72 wk of age) were individually fed a basal ration of 75% ground barley straw and 25% ground bromegrass hay [total digestible nutrients=46.3, crude protein (CP)=7.5 (% dry matter (DM))]. Heifers were supplemented with either (1) no supplement (CONT); (2) dried distillers' grains plus solubles [70:30 wheat:corn blend; dried distillers' grains plus solubles (DDGS)]; (3) commercial range pellet (COMM); or (4) barley grain and canola meal (BAR+CM). Forage intake, apparent total tract digestibility, passage rate, rate and extent of forage degradation, rumen pH and rumen ammonia nitrogen were measured. Forage intake, passage rate, and apparent total tract digestibility of DM, neutral detergent fiber, and acid detergent fiber were unaffected (P>0.41) by treatment. Apparent total tract digestibility of CP was increased (P=0.02) with supplements as compared with CONT, but did not differ (P>0.05) among DDGS, COMM, and BAR+CM. Ruminal pH was not affected (P=0.20) by treatment, but rumen ammonia-N was increased (P<0.01) with all three supplements. Potentially degradable and undegradable forage fractions were decreased (P<0.02) and there was a tendency (P=0.06) for the rate of forage DM degradation to increase with supplementation. Supplementing forage diets with either DDGS, grain-soybean-canola- or grain-canola-based supplements did not increase the intake or digestibility of a forage-based diet. More research, however, is required to study the feasibility of feeding these supplements at greater levels with forage-based beef cattle diets.

The effect of dietary ratios of corn silage and alfalfa hay on carbohydrate digestion and retention time of feed particles in the gastrointestinal tract of steers

Four Holstein steers fitted with duodenal cannula were used in a 4 x 4 Latin square design to investigate the effect of the combination of corn silage (CS) and alfalfa hay (AH) in different ratios on the ruminal and intestinal digestion of carbohydrates and feed particle passage rate. Steers were fed mixed diets containing both CS and AH in ratios of 80:20, 60:40, 40:60 and 20:80 on a dry matter basis at 95% of ad libitum feed intake. The increase of AH proportion in diets increased dry matter intake and ruminal digestion of dry matter, non-fiber carbohydrate, neutral and acid detergent fiber linearly. Ruminal digestibility of neutral detergent fiber showed a quadratic response, and total digestibility increased linearly with increasing AH proportion. Digestibility of acid detergent fiber in the rumen was not affected by the dietary treatments, but the total tract digestibility increased as the AH proportion increased. Mean retention time of feed particles in total compartment increased when the AH proportion increased from 20% to 60%, but decreased with further increase of the AH proportion. These results indicate that moderate combinations of CS and AH have an associative effect on ruminal fiber digestion, modifying particle movement in the rumen.