Feeding value of whole raw soya beans as a protein supplement for beef cattle consuming low-quality forages.

Experiments (Exp) I and II were conducted to compare raw whole soya beans (WSB), roasted (rWSB) or other protein sources as supplements of low-quality forages fed ad libitum to beef cattle, upon DM intake (DMI), ruminal and blood parameters, and animal performance. Exp I: treatments for wheat straw fed to four ruminally cannulated steers were (i) Control-WS: no supplement; (ii) WSB-WS: whole soya beans; (iii) rWSB-WS: roasted WSB; and (iv) SBM-WS: soybean meal-wheat midds mixture; all fed at 1.4 kg DM/day. Exp II: 12 steers grazed deferred grain sorghum (DS) receiving these treatments: (i) Control-DS: no supplement; (ii) WSB-DS: 1.26 kg DM/day whole soya beans; and (iii) SFM-DS: 1.35 kg DM/day of sunflower meal. In Exp I, WS DMI resulted 47, 52 and 41% greater for WSB-WS, rWSB-WS and SBM-WS, respectively, than Control-WS (p < .05). In Exp II, the DMI of DS was unaffected by supplementation; a substitution of DS by supplement was found for WSB-DS (p < .05); however, total diet and digestible DMI increased with supplementation (p < .05). Rumen pH in Exp I remained unaffected by supplementation, but N-NH3 as well as blood urea-N in Exp II increased (p < .05). In Exp II, average daily weight gains improved similarly with both supplements compared with Control-DS. Additionally, feed-to-gain ratio decreased (p < .05), being lower for WSB-DS (8.3) vs. SFM-DS (9.9). Roasting effects of WSB as a supplement for low-quality forages were not detected, and all protein sources increased total diet DMI and forage utilization. Only moderate cattle weight gains could be expected for unsupplemented DS.

Effects of supplemental zinc and manganese on ruminal fermentation, forage intake, and digestion by cattle fed prairie hay and urea.

One in vitro and one in vivo metabolism experiment were conducted to examine the effects of supplemental Zn on ruminal parameters, digestion, and DMI by heifers fed low-quality prairie hay supplemented with urea. In Exp. 1, prairie hay was incubated in vitro for 24 h with five different concentrations of supplemental Zn (0, 5, 10, 15, and 20 ppm) and two concentrations of supplemental Mn (0 and 100 ppm), both provided as chloride salts. Added Mn increased (P < 0.02) IVDMD, but added Zn linearly decreased (P < 0.03) IVDMD. Added Zn tended to increase the amount of residual urea linearly (P < 0.06) at 120 min and quadratically (P < 0.02) at 180 min of incubation, although added Mn counteracted these effects of added Zn. Six 363-kg heifers in two simultaneous 3 x 3 Latin squares were fed prairie hay and dosed once daily via ruminal cannulas with urea (45 or 90 g/d) and with Zn chloride to provide the equivalent of an additional 30 (the dietary requirement), 250, or 470 ppm of dietary Zn. After a 7-d adaptation period, ruminal contents were sampled 2, 4, 6, 12, 18, 21, and 24 h after the supplement was dosed. Supplemental Zn did not alter prairie hay DMI (mean = 4.9 kg/d) or digestibility, although 470 ppm added Zn tended to decrease (P < 0.06) intake of digestible DM, primarily due to a trend for reduced digestibility with 470 ppm supplemental Zn. Zinc x time interactions were detected for both pH (P = 0.06) and NH3 (P = 0.06). At 2 h after dosing, ruminal pH and ruminal ammonia were linearly decreased (P < 0.05; P < 0.01) by added Zn. At 5 h after feeding, ruminal pH was linearly increased (P < 0.05) by added Zn, suggesting that added Zn delayed ammonia release from urea. The molar proportion of propionate in ruminal fluid was linearly and quadratically increased (P < 0.02; P < 0.01) whereas the acetate:propionate ratio was linearly and quadratically decreased (P = 0.02; P < 0.05) by added Zn. Through retarding ammonia release from urea and increasing the proportion of propionate in ruminal VFA, Zn supplementation at a concentration of 250 ppm may decrease the likelihood of urea toxicity and increase energetic efficiency of ruminal fermentation.

Leaf ruminal digestion in Sorghum bicolor cultivars as influenced by water deficit.

A study was carried out on the effects of water deficit upon the specific leaf digestion of two sorghum cultivars: Novillero and Leoti Red. Using scanning electron microscopy it was established that after ruminal incubation, losses of structural integrity increased when the plants were submitted to drought conditions. This increase was marked in cv. Novillero after 48 h of digestion. For both cultivars, the phloem, mesophyll, parenchyma and epidermis were the most susceptible tissues to bacterial attack. The alterations in tissue disappearance during digestion, could partially explain the effects of water deficit upon the improvement in the nutritional quality of the two cultivars studied.

Leaf ruminal digestion in Sorghum bicolor cultivars as influenced by water deficit

A study was carried out on the effects of water deficit upon the specific leaf digestion of two sorghum cultivars: Novillero and Leoti Red. Using scanning electron microscopy it was established that after ruminal incubation, losses of structural integrity increased when the plants were submitted to drought conditions. This increase was marked in cv. Novillero after 48 h of digestion. For both cultivars, the phloem, mesophyll, parenchyma and epidermis were the most susceptible tissues to bacterial attack. The alterations in tissue disappearance during digestion, could partially explain the effects of water deficit upon the improvement in the nutritional quality of the two cultivars studied.

Leaf ruminal digestion in Sorghum bicolor cultivars as influenced by water deficit

A study was carried out on the effects of water deficit upon the specific leaf digestion of two sorghum cultivars: Novillero and Leoti Red. Using scanning electron microscopy it was established that after ruminal incubation, losses of structural integrity increased when the plants were submitted to drought conditions. This increase was marked in cv. Novillero after 48 h of digestion. For both cultivars, the phloem, mesophyll, parenchyma and epidermis were the most susceptible tissues to bacterial attack. The alterations in tissue disappearance during digestion, could partially explain the effects of water deficit upon the improvement in the nutritional quality of the two cultivars studied.

Leaf ruminal digestion in Sorghum bicolor cultivars as influenced by water deficit.

A study was carried out on the effects of water deficit upon the specific leaf digestion of two sorghum cultivars: Novillero and Leoti Red. Using scanning electron microscopy it was established that after ruminal incubation, losses of structural integrity increased when the plants were submitted to drought conditions. This increase was marked in cv. Novillero after 48 h of digestion. For both cultivars, the phloem, mesophyll, parenchyma and epidermis were the most susceptible tissues to bacterial attack. The alterations in tissue disappearance during digestion, could partially explain the effects of water deficit upon the improvement in the nutritional quality of the two cultivars studied.

Leaf ruminal digestion in Sorghum bicolor cultivars as influenced by water deficit.

A study was carried out on the effects of water deficit upon the specific leaf digestion of two sorghum cultivars: Novillero and Leoti Red. Using scanning electron microscopy it was established that after ruminal incubation, losses of structural integrity increased when the plants were submitted to drought conditions. This increase was marked in cv. Novillero after 48 h of digestion. For both cultivars, the phloem, mesophyll, parenchyma and epidermis were the most susceptible tissues to bacterial attack. The alterations in tissue disappearance during digestion, could partially explain the effects of water deficit upon the improvement in the nutritional quality of the two cultivars studied.