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.

Persistence of the effects of early experience on consumption of low-quality roughage by sheep.

The aim of this study was to determine the effects of experience early in life with cured weeping lovegrass (Eragrostis curvula) (low-quality roughage) or fresh oats (Avena sativa) (high-quality roughage) on voluntary intake and nitrogen retention when sheep ate a low-quality roughage 9 mo after initial exposure. From 1 to 5 mo of age, experienced wethers (EW) grazed cured weeping lovegrass, whereas inexperienced wethers (IW) grazed fresh oats (initial exposure). Then both EW and IW were fed sorghum (Sorghum bicolor) hay for 45 d, fresh weeping lovegrass for 105 d, and finally alfalfa hay for 120 d. Nine months after completion of the initial exposure EW and IW were offered sorghum hay (low-quality roughage), and, in addition, both groups were offered sorghum with ad libitum access simultaneously to alfalfa hay at six levels of availability. Experienced wethers ingested 15% more (P < .02) sorghum than IW. When given sorghum simultaneously with alfalfa at different levels of availability, EW ingested more (P < .10) sorghum than IW when only sorghum was freely available. Nitrogen retention was negative in both groups, but it was less negative in EW than in IW per unit of metabolic weight (P < .09) and per wether (P < .04). The results show that early dietary experience can have profound and persistent effects on consumption of foods low in nutritional quality, apparently through changes in critical physiological mechanisms.

Effects of early experience on voluntary intake of low-quality roughage by sheep.

This study determined 1) how experience early in life with cured weeping lovegrass (Eragrostis curvula) (low-quality roughage) or fresh oats (Avena sativa) (high-quality roughage) affected consumption of low- or high-quality roughage by lambs later in life and 2) whether this early dietary experience affected passage of undigested residues through the digestive tract and digestion of low-quality roughage. From 1 to 5 mo of age, experienced lambs (EL) were grazing cured weeping lovegrass, whereas inexperienced lambs (IL) were grazing fresh oats. Immediately after exposure, in Trial 1 lambs were fed sorghum (Sorghum bicolor) hay (low-quality roughage) supplemented with a protein concentrate. In Trial 2 lambs were offered sorghum only. Finally, in Trial 3 lambs were offered a choice between sorghum and alfalfa hay. When the sorghum was supplemented with protein there was no difference (P > .05) between treatments in intake of sorghum, but when the supplement was withheld in Trial 2, EL ingested 20% more (P < .01) sorghum than IL. When given a choice between sorghum and alfalfa, EL ingested 2.5 times more (P < .01) sorghum than IL. The apparent digestibility of sorghum was 4.5% higher (P < .01) in EL than in IL, whereas passage of undigested matter through the digestive tract was similar (P > .05). The results show that early dietary experience can have a significant effect on consumption of low-quality roughage and diet selection in free-choice situations.

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.