Ruminal Microbial Degradation of Individual Amino Acids from Heat-Treated Soyabean Meal and Corn Gluten Meal in Continuous Culture.

Eight dual-flow continuous culture fermenters were used in three periods to study the effects of diets containing heat-treated soyabean meal (HSBM) or corn gluten meal (CGM) on ruminal microbial fermentation and the degradation of individual amino acids (AA). Treatments were a mix of non-protein nitrogen (N; urea and tryptone) that were progressively substituted (0, 33, 67 and 100%) for HSBM or CGM. Ruminal escape of AA was calculated with the slope ratio technique. Total volatile fatty acids (95.0 mM) and molar proportions (mol/100 mol) of acetate (59.3), propionate (21.8) and butyrate (10.5) were not affected by the treatments. As the level of HSBM or CGM increased, the concentration of ammonia-N and the degradation of protein decreased (p < 0.01), and the flows of nonammonia and dietary N increased (p < 0.01) quadratically. Compared with HSBM, CGM provided the highest flow (g/d) of total (20.6 vs. 18.3, p < 0.01), essential (9.04 vs. 8.25, p < 0.04) and nonessential (11.5 vs. 10.0, p < 0.01) AA, and increased linearly (p < 0.01) as the level of supplemental protein increased. Ruminal degradation of essential AA was higher (p < 0.04) than nonessential AA in CGM, but not in HSBM. Degradation of lysine was higher (p < 0.01) in both proteins, and degradation of methionine was higher in CGM. Ruminal degradation of individual AAs differ within and between protein sources and needs to be considered in precision feeding models.

Effects of replacing canola meal with camelina expeller on intake, total tract digestibility, and feeding behavior of beef heifers fed high-concentrate diets.

To assess the effect of inclusion of camelina expeller in beef cattle diets, 24 Simmental heifers were used. Two experiments were carried out. In the first, two free-choice tests, one without and another with molasses, were conducted to know the preference of animals for a total mixed ration (TMR) made with a 90 to 10 concentrate to barley straw ratio, where canola meal (CM) or camelina expeller (CE) was used in the concentrate as a protein source. Heifers were allotted in four pens with two independent feedbunks, one for each diet. In the second, a replicated 4 × 4 Latin square design was used to assess the effects of the replacement of CM with CE on intake, digestibility, and sorting and animal behavior. The experiment was performed in four 28-d periods during which groups of three animals were allotted in each pen of 12.5 m2. Diets were formulated with a 90 to 10 concentrate to barley straw ratio and fed as TMR, and they were designed to contain 1) CM as main protein source and 0% of CE (0CE), 2) 3% of CE replacing CM (3CE), 3) 6% of CE replacing CM (6CE), and 4) 9% of CE replacing CM (9CE). In the free-choice test without molasses, heifers showed a greater preference for CM than for CE (38.6 vs. 8.7 kg/d; P < 0.001). When molasses were added to the diet, the preference for CM was maintained (39.1 vs. 9.8 kg/d; P < 0.001). Dry matter (DM), organic matter (OM), crude protein (CP), and neutral detergent fiber (NDF) intake was unaffected by the level of replacement of CM by CE (P > 0.10), and there was no effect of this replacement on DM, OM, CP, and NDF apparent digestibility (P > 0.10). Intake of long particle size increased lineally as CE proportion increased (P = 0.015). In addition, extension of sorting behavior for long particle size tended to increase lineally (P = 0.07), and sorting against this particle size was detected in 0CE and 3CE, but not in 6CE and 9CE (P < 0.05). However, the results recorded for long particle size intake and for sorting behavior against these particles did not translate into more time spent ruminating in heifers fed diets with higher proportion of CE. In conclusion, when canola meal was replaced with camelina expeller at more than 14% of inclusion, heifers preferred the canola meal diet. However, replacing canola meal with camelina expeller up to 9% of inclusion in diets for beef cattle did not affect intake and digestibility but promoted a greater intake of long particle size of barley straw.

Increasing the content of physically effective fiber in high-concentrate diets fed to beef heifers affects intake, sorting behavior, time spent ruminating, and rumen pH.

AbstractThe importance of fiber particle size in ruminal health is well known, but there are fewer studies to assess the requirements of physically effective NDF (peNDF) in beef cattle than in dairy cattle. The objective of this study was to establish the optimal peNDF proportion in high-concentrate diets fed to beef cattle, to reduce the risk of subacute ruminal acidosis. The experimental design was a replicated Latin Square 4 × 4, with four periods of 21 d. Treatments consisted of four diets with different peNDF proportions: 6.4%, 10.4%, 13.6%, and 15.4%, offered ad libitum as total mixed ration, and containing 15% barley straw and 85% concentrate. Diets, which differed in proportions of straw > 4 mm (considered peNDF) and straw < 4 mm, were manually mixed with concentrate. This concentrate was the same for all diets. A ruminal bolus was orally administered to each heifer for pH measurement. Intake, water consumption, intake by particle size, feed sorting, feeding behavior, behavioral activities, and rumen pH were recorded. Chemical composition and particle sizes of diets offered were assessed in the last week of each period. Data were analyzed using the MIXED procedure of SAS. Orthogonal contrasts determined the linear and quadratic effects of increasing peNDF proportion. T-test procedure determined whether heifers carried out sorting behavior. Particles >4 mm linearly increased (P = 0.001), and particles <4 mm linearly decreased (P = 0.001) as peNDF increased. Water consumption and feeding behavior were unaffected by treatment. As peNDF increased, intakes of DM and NDF linearly decreased (P = 0.001), whereas peNDF intake increased (P = 0.001). Intake of particles > 4 mm linearly increased, whereas intake of particles < 4 mm linearly decreased (P = 0.001) as peNDF increased. Diet 6.4% performed sorting for particles > 4 mm (P < 0.01), and diets 13.6% and 15.4% against particles > 4 mm (P < 0.01). Diet 10.4% tended to sort against particles > 4 mm (P < 0.10). Time spent ruminating linearly increased (P = 0.001) as peNDF increased. Diets did not differ in mean and minimum rumen pH, but time under rumen pH thresholds (5.8, 5.7, 5.6, and 5.5) linearly decreased as peNDF increased (P < 0.05). The results suggested that the diet that best met the requirements of not compromising intake, limiting sorting behavior, and promoting time spent ruminating to reduce the number of hours under rumen pH thresholds, was the 10.4% diet.

Effects of Capsicum and Propyl-Propane Thiosulfonate on Rumen Fermentation, Digestion, and Milk Production and Composition in Dairy Cows.

Essential oils may affect rumen fermentation, nutrient digestion, and milk production and composition. The objective of this study was to test the effects of capsicum oleoresin (CAP) and propyl-propane thiosulfonate (PTSO) on rumen fermentation, total tract digestibility, and milk yield and composition in lactating dairy cattle. Six lactating Holstein cows (averaging (mean ± SD) 130 ± 40 days in milk and 723 ± 55 kg of body weight) fitted with rumen cannulae were used in a duplicated 3 × 3 Latin square design. Treatments were: a control diet (CTR), the CTR diet with the addition of 500 mg/d/cow of CAP, and the CTR diet with the addition of 250 mg/d/cow of PTSO. Dry matter intake (DMI) averaged 20.7 kg/d with a tendency towards higher intake in cows fed CAP and lower in those fed PTSO (p = 0.08). Milk yield averaged 31.8 kg/d with no difference among treatments. However, feed efficiency was higher in PTSO supplemented cows compared with CTR (1.65 and 1.41 kg of milk yield/kg of DMI, respectively; p < 0.01). At the doses used in this experiment, CAP and PTSO failed to demonstrate any effects on rumen fermentation, but PTSO increased the efficiency of feed utilization to produce milk.

Exploring Additive, Synergistic or Antagonistic Effects of Natural Plant Extracts on In Vitro Beef Feedlot-Type Rumen Microbial Fermentation Conditions.

Six Essential oils (EO) (tea tree oil-TeTr, oregano oil-Ore, clove bud oil-Clo, thyme oil-Thy, rosemary oil-Ros, and sage oil-Sag) in Experiment 1; and different combinations of selected oils in Experiment 2, were evaluate at four doses in an in vitro microbial fermentation system using ruminal fluid from beef cattle fed a 10:90 straw: Concentrate diet. In Experiment 1, TeTr, Ore, Clo and Thy improved rumen fermentation profile in a direction consistent with better feed utilization. In Experiment 2, TeTr mixed with Thy, Ore, Thy + Ore or Clo at 200 and 400 mg/L increased the molar proportion of propionate and decreased that of acetate, and the acetate to propionate ratio. However, the size of the effect was similar to that obtained with TeTr alone, suggesting that effects were not additive. When Thy, Ore or Thy + Ore where mixed with Clo, most effects on rumen fermentation profile disappeared, suggesting an antagonistic interaction of Clo with Thy and Ore. Results do not support the hypothesis of additivity among the EO tested, and antagonistic effects of Clo mixed with Thy or Ore were demonstrated at least in a low pH, beef-type fermentation conditions.

In vitro Digestibility, In situ Degradability, Rumen Fermentation and N Metabolism of Camelina Co-Products for Beef Cattle Studied with A Dual Flow Continuous Culture System of Camelina Co-Products for Beef Cattle.

Camelina meal (CM) and camelina expeller (CE) were compared with soybean meal (SM) and rapeseed meal (RM). Trial 1 consisted of a modified Tilley and Terry in vitro technique. Trial 2 was an in situ technique performed by incubating nylon bags within cannulated cows. Trial 3 consisted in dual-flow continuous culture fermenters. In Trial 1, CM, CE and RM showed similar DM digestibility and OM digestibility, and SM was the most digestible ingredient (p < 0.05). Trial 2 showed that CE had the numerically highest DM degradability, but CP degradability was similar to RM. Camelina meal had a DM degradability similar to SM and RM and had an intermediate coefficient of CP degradability. In Trial 3, CE diet tended to present a higher true OM digestibility than SM diet (p = 0.06). Total volatile fatty acids (VFA) was higher in CE and CM diets than in SM diet (p = 0.009). Crude protein degradation tended to be higher (p = 0.07), and dietary nitrogen flow tended to be lower (p = 0.06) in CE diet than in CM diet. The efficiency of microbial protein synthesis was not affected by treatment (p > 0.05). In conclusion, CE and CM as protein sources differ in CP coefficient of degradability but their results were similar to RM. More differences were detected with regard to SM.

Using 19% of alfalfa hay in beef feedlot finishing diets did not modify meat quality but increased feed intake and ADG1.

To evaluate the effects of including extra alfalfa hay (AH) in high-concentrate diets fed to beef heifers on intake, ADG, G:F, and carcass and meat quality, we used 24 Simmental heifers (initial BW 235.6 ± 4.19 kg). Heifers were blocked in four BW blocks and allotted in groups of 3 in a randomized block design with 2 treatments and 12 heifers per treatment. Treatment diets offered as total mixed ration (TMR) were (i) TMR with 10% barley straw (BS), considered the control diet, and (ii) TMR with 19% AH. The experiment was performed over four 28-d experimental periods, and we took measurements in the last week of each period. After this period of performance control, heifers were fed the corresponding diet until each BW block reached the target weight of 400 kg on average. Feed intake and ADG were greater for AH than BS (9.5 vs. 8.4 kg/d, and 1.45 vs. 1.29 kg/d, respectively; P < 0.05), but G:F was unaffected by diet (P > 0.10). Diet did not affect HCW, dressing percentage, backfat color, pH and meat color, or carcass grade. The sixth rib was dissected to determine the proportion of fat, lean, and bone, which were unaffected by diet. Diet did not affect the LM composition in water, protein, collagen, intramuscular fat, and cholesterol. The intramuscular fat proportion of C18:1 n-7 was greater in BS than in AH (P = 0.016), whereas the proportion of C18:3 n-3 tended to be greater in AH than in BS (P = 0.09). When fatty acid concentration was expressed as gram per 100 g of LM, these differences disappeared, and only the content of C15:0 tended to be greater (P = 0.08) in BS than in AH. Meat characteristics evaluated by trained panelists did not differ in toughness, chewiness, juiciness, odor, taste, and overall acceptability, and there were no differences between diets in Warner-Bratzler shear force values after 3 or 10 d of aging (P > 0.10). In summary, heifers fed TMR with AH at 19% of inclusion showed a greater feed intake and ADG than those fed BS at 10% of inclusion, but without affecting G:F ratio. However, this extra AH was not sufficient to cause any relevant change in the carcass and meat quality of the heifers fed this diet.

Effects of live yeast (Saccharomyces cerevisiae) and type of cereal on rumen microbial fermentation in a dual flow continuous culture fermentation system.

Live yeast additives may help optimize ruminal fermentation of high-grain diets, especially when the starch of the ration is highly fermentable. Eight dual flow continuous culture fermenters were used in a 2 × 2 factorial design in two replicated periods of 9 days (six for adaptation and three for sampling) to determine the effect of live yeast and type of cereal on rumen microbial fermentation and nutrient digestibility. Main factors were the addition of live yeast: no yeast (NY) vs. 2 × 107 CFU of yeast/g of diet (LY); and type of cereal in the diet: corn (CO) vs. barley (BA). All fermenters were fed 80 g dry matter/day of a 10-90 forage to concentrate diet and pH was allowed to fluctuate with an upper (6.6) and lower (5.5) limit. Treatment BA increased OM digestion, valerate proportion, peptides and ammonia N fractions, ammonia N flow, crude protein degradation and target copies of Megasphaera elsdenii; and decreased NDF digestion, propionate proportion, branched-chain VFA (BCVFA) concentration, AA-N fraction and nonammonia N flow. Treatment LY increased BCVFA and decreased ammonia N fraction and flow, and the target copies of Streptococcus bovis. Treatment LY decreased the slope of pH drop, the area under pH 6.0 and the gas production. These results suggest potential benefits of LY in stabilizing the fermentation of BA-based diets.