Joseph P. Fontenot

The effects of short-term and long-term monensin supplementation, and its subsequent withdrawal on digestion in sheep

Eight Texel adult wethers fitted with ruminal and duodenal simple cannulas were divided into two groups and used for four periods to ascertain whether rumen microbes can adapt to monensin. The animals were fed on a control diet to establish control values during period 1. During period 2 one group remained on this diet while the other group received a monensin supplemented diet. Period 3 began 96 days after the animals first received the supplemented diet to study any effect of adaptation to monensin. The antibiotic was removed during period 4 to study any lasting effect. Animals received a pelleted diet composed of prairie hay (43.3%), maize grain (34.4%), lupin grain (20.7%) and mineral mixture given at 45 g kg−1 BW0.75 (1000 g dry matter (DM) day−1) together with 100 g wheat straw. DM and organic matter (OM) digestibility were increased (P < 0.05) during both periods of monensin supplementation. These effects disappeared after ionophore withdrawal. Monensin had no effect on postruminal digestion of OM. Starch digestion was not altered by monensin treatment. The ionophore antibiotic decreased (P < 0.05) total volatile fatty acid (VFA) concentrations after the 96 day period of supplementation. It decreased (P < 0.05) ruminal acetate and butyrate molar proportions while increasing (P < 0.05) that of propionate in the VFA mixture. Samples taken at weekly intervals throughout the experiment showed that monensin established its effects on acetate, propionate and butyrate within 7 days of administration. After its withdrawal, VFA returned to control values within 24 h. Monensin supplementation caused a greater decrease in the concentration of rumen protozoa in the short term than in the long-term period of treatment. The ionophore increased (P < 0.05) the apparent digestibility of N only during the short-term period, but did not alter non-ammonia nitrogen (NAN) flow in the duodenum whilst that of NH3-N decreased (P < 0.05). The flow of bacterial N increased (P < 0.05) only after the long-term period of treatment. There were no treatment effects on the mean retention time of solid particles nor on the turnover rate and the volume of ruminal liquid phase. Considering overall results, we can conclude that there is no real adaptation of rumen microbes after a period of 96–146 days of monensin treatment and that most effects disappear within a few hours following monensin withdrawal.

Lignin impact on fibre degradation. 2. A model study using cellulosic hydrogels

The impact of lignin on cellulose degradation was studied in vitro using lignocellulosic hydrogels. Hardwood lignin (methoxyl content, 191 mg g -1 ) was blended with cellulose in homogeneous phase solution (dimethylacetamide/LiCl solvent) in two concentrations (100 and 300 mg g -1 ) and formed into lignocellulosic beads by dropwise addition of the lignocellulose solutions to an appropriate nonsolvent. The lignin was used before and after hydroxypropylation of the phenolic hydroxyl group. Cellulose degradation from these beads after 24 and 72 h incubation in buffered ruminal fluid was compared to that of control (cellulose) beads and to that of cellulose beads incubated in the presence of lignin. The rate of cellulose degradation from the hydrogels was low (12-16% degradation after 24 h). At 72 h, 21-50% of the cellulose was degraded. Cellulose degradation was enhanced (P < 0.01) by lignin blended into the beads, but depressed (P < 0.01) by lignin added to the incubation medium. The effect of lignin increased (P<0.001) with lignin concentration. Hydroxypropylation of lignin, which blocks the formation of quinone methide intermediates, enhanced (P < 0.001) the increase in cellulose degradation with lignin blending, and reduced (P < 0.001) the inhibitory effect of lignin included in the incubation medium.

Nutritive value of deep stacked and ensiled broiler litter for sheep

Broiler litter was deep stacked and ensiled with water to achieved 40% moisture before being added, with or without 5% sugarcane molasses or with rumen contents, to a basal diet. The influence of stacking and ensiling of broiler litter on the numbers of Salmonella, Shigella, Proteus and total number of colony forming units (CFU) was investigated. Nutritive value of broiler litter processed by deep stacking and ensiling was evaluated in a digestibility trial. The experiment was conducted with 30 wethers allotted to five diets. A basal diet (20% corn grain, 23% wheat bran, 37% cotton seed cake, 18% wheat straw and 2% dicalcium phosphate) was given alone (1) or with broiler litter processed by deep stacking (2), ensiling (3), ensiling with 5% added molasses (4), or ensiling with rumen contents (1:1, wet basis) (5). For Diets 2–5, the ratio of basal diet to silage was 1:1, dry basis. For the digestion trial, diets were given at 20 g dry matter (DM) kg−1 body weight per day. Initial samples of broiler litter showed 2.5 × 108 CFU and Salmonella, Shigella and Proteus were present. The processes of deep stacking and ensiling were equally effective in achieving a complete elimination of all the pathogens. Apparent digestibilities of organic matter (OM) and crude protein (CP) (559.1 g kg−1 and 608.7 g kg−1 DM) were lower (P < 0.05) for diet 2 (deep stacked litter) than for the other waste-containing diets (OM: 578.7 g kg−1, 582.9 g kg−1, 594.1 g kg−1; CP: 688.6 g kg−1, 675.8 g kg−1, 709.0 g kg−1 DM, for Diets 3, 4 and 5, respectively). Among the waste-containing diets, cellulose digestibility (398.7 g kg−1 DM) was higher (P < 0.05) for Diet 5 (ensiled litter-rumen contents). The results indicate that deep stacking and ensiling are equally feasible and effective for eliminating the pathogens and processed broiler litter can be incorporated in the diet of ruminants at levels of up to 50% without any adverse effect on the health of the animals.

Processing and nutritive evaluation of broiler litter as livestock feed

Broiler litter was deep stacked at 30 and 40% moisture or ensiled at 40% moisture for 6 weeks in quadruplicate and subsequently evaluated for changes in chemical composition, pathogenic microbial load and in vitro dry matter degradability (IVDMD). A metabolism trial was conducted with lambs, in which a low-protein basal diet supplemented with litter, deep stacked at 30% and 40% moisture for 6 weeks or ensiled were compared with an isocaloric, isonitrogenous soybean meal supplemented diet. The maximum stack temperature of 65°C (irrespective of moisture level) was attained on day 7 at 45 cm depth and 60.5°C on day 10 at 80 cm depth, which eliminated coliforms. Increases in lactic and acetic acids were recorded with increase in moisture levels and advancement of stacking period. A small increase in crude protein (CP) content was associated with considerable declines in organic matter (OM), cellulose, neutral detergent fiber (NDF) and hemicellulose in deep-stacked litters. The apparent digestibility of nutrients and N-retention in the litter-supplemented diets were similar to those of the soybean meal supplemented diet. It is concluded that by deep stacking at 30 or 40% moisture, or ensiling, the litter was rendered free of pathogens and could be incorporated in the diet of livestock without adversely affecting digestibility of fiber and efficiency of N utilization.

Fermentation characteristics of ensiled seafood wastes and low-quality roughages.

Abstract Experiments were conducted to investigate the chemical composition of seafood waste and the ensiling characteristics of seafood waste combined with low-quality roughages. Average crude protein of the fish and crab wastes was 60.4% and 44.1%, dry basis, respectively. Fish and crab processing wastes were ground and ensiled with corn stover or peanut hulls in proportions to result in dry matter (DM) levels of 40, 50 and 60% alone and with 5% dry molasses or 1% formic acid in 3.8 1 cardboard containers double-lined with polyethylene. The seafood wastes were also ensiled with wilted Johnsongrass (50:50, wet basis) with and without 5% dry molasses. All silages had desirable aroma except those with crab waste ensiled at 40 and 50% DM. After ensiling average pH for mixtures with fish waste was 6.5, compared with 8.0 for mixtures with crab waste. Addition of dry molasses decreased pH of the ensiled fish-waste mixtures, but had no effect on the crab-waste mixtures. Coliforms and fecal coliforms were decreased or eliminated by ensiling. Finfish wastes and crab processing wastes were mixed with wheat straw and ensiled in 210-1 metal drums, double-lined with polyethylene. Proportions of fish waste and straw were 70:30 and 51:49, wet basis, and those for the crab waste were 60:40 and 40:60, wet basis, respectively. Dry molasses (5%) was included in all mixtures and acetic acid was added to the crab-waste mixture to lower the initial pH to 4.5. Mixtures containing fish waste and straw decreased in pH after ensiling, the decrease being large for the mixture with the lower proportion of fish waste. Lactic acid concentrations were inversely related to pH. In the crab waste-straw mixtures, pH remained below 5, and essentially no lactic acid was present.

Effect of processing method on ruminal solubility and degradability of broiler litter

Abstract Ruminal crude protein (CP) degradability and solubility of ensiled, deepstacked, and composted broiler litter were determined in situ and in vitro, and compared to soybean meal. The estimated ruminal degradability of CP was 75·2% for soybean meal and 89–94% for broiler litter. Ruminal degradability of dry matter (DM) of broiler litter processed by different methods was 66–69%, and that of soybean meal was 77·9%. Degradability of DM of deepstacked litter from private farms was lower ( P s 0·05 ) in the surface and charred areas, compared with normal brown, properly preserved litter within the stack. Results indicate that nutritional value of broiler litter for ruminants is affected by soluble and degradable DM and CP. The nutritional value may be reduced by improper storage.