The effect of the stage of maturity on the productivity, chemical composition, and ruminal degradability of Napier grass (Pennisetum purpureum) leaves under irrigation was studied. Samples were collected at three stages of maturity, at intervals of four weeks starting from the fourth week until the twelfth week (AprilJuly) after sprouting and then harvested to determine biomass. The stages of maturity had significant effects on longest leaf length per plant and plant height, but had no effect on number of leaves per plant and number of tillers. Dry matter (DM) increased significantly with maturity, while crude protein (CP) and fat content decreased significantly, with no significant effect on acid detergent lignin (ADL), ash, acid detergent fibre (ADF) and neutral detergent fibre (NDF). Maturity significantly decreased potassium, copper and sodium, while calcium and zinc increased significantly up to the intermediate stage, then declined toward the late stage of maturity. Maturity did not affect the magnesium, phosphorus, manganese and iron contents of the forage. Ruminal degradability of CP at 48, 72, 96 and 120 incubation hour decreased significantly with maturity, with no effect on all other incubation times for DM and CP. Maturity significantly decreased the soluble fraction (a) of DM, with no significant effect on other fractions of DM and CP. Effective degradability (%) of DM and CP decreased with maturity when the rate of passage increased from 2% to 8%. Napier forage should be harvested before maturity to retain its high nutrient content, and the degradability of DM and CP. ______________________________________________________________________________________

Dry seasons pose a major nutritional constraint on ruminant livestock production in tropical regions, which justifies forage conservation to meet the dry season feed requirement. Napier grass is a tropical forage that is used for silage in South Africa. The present objective was to determine the effects of Napier grass fertilization with bio-digester slurry (BDS) and the inclusion of fermentable carbohydrate additives at ensiling on the chemical composition and ruminal degradability of Napier grass silage. Napier grass was established in 5 x 4 metre plots, replicated three times in a completely randomized design, and irrigated weekly with either BDS or water. After 12 weeks, the Napier was cut and ensiled for 90 days in 1 liter glass jars in a 2 (BDS, Water) x 4 (no-additive, molasses, brown sugar, and maize meal) factorial arrangement replicated three times. The nutrient composition was determined using standard protocols. The ruminal degradability of dry matter (DM) and crude protein (CP) were determined using the nylon bag technique. Fertilization with BDS increased (p < 0.05) pH and CP and reduced (p < 0.05) fat content of fresh cut Napier. Additives increased (p < 0.01) silage DM content and reduced (p < 0.01) ADF, NDF content. The BDS fertilization with molasses inclusion increased (p < 0.05) silage DM relative to the no-additive and maize meal inclusion, and decreased (p < 0.05) fat content compared to the no-fertilizer, added maize meal silage.. Molasses increased silage WSC and decreased the NH3-N content (p < 0.05) compared to the no-additive and maize meal treatments. For DM, the BDS fertilized, no additive silage had the least “a” fraction (p<0.01), while the no BDS, no- additive silage had the least “b” fraction (p<0.01), with least (p<0.01) potential degradability observed for the no BDS, no-additive treatment. Fertilization increased (p<0.01) effective degradability of DM at outflow rates k = 0.02, 0.05, 0.08, with same effect for molasses and maize meal inclusion. Relative to the control, molasses inclusion increased (p<0.01) potential degradability of silage CP. In conclusion, our results suggested BDS fertilization of Napier grass ensiling with added readily fermentable carbohydrate substrate, particularly from molasses, induced changes in silage chemical and fermentation characteristics likely to promote better forage preservation and ruminal microbial function.

The study examined the effects of botanical factors and fermentation-based, high-level dilution of coproduct feeds in maize-soybean growing-pig diets on enzymatic insoluble fibre hydrolysis and fermentation. Feed insoluble fibre residues that were recovered after pepsin-pancreatin digestion were subjected to Roxazyme ® G2 (Roxazyme) versus Viscozyme L ® V2010 (control) hydrolysis, and to 64-hour fermentation using pig faecal inoculum. The control diet was a 13 MJ metabolizable energy, 141 g total dietary fibre/kg dry matter maize-meal/hominy chop-soybean diet, which was diluted with maize cob, soybean hulls, barley brewer's grains, lucerne hay or wheat bran in 12 MJ metabolizable energy, 246 g total dietary fibre/kg dry matter iso-nutrient, single co-product test diets. Fermentable insoluble fibre was employed in a computerized iterative selection of ingredients in two iso-nutrient 11 MJ metabolizable energy 319 total dietary fibre/kg dry matter mixed fibre test diets for maximal contrast (high (HF) versus low (LF)) in fermentability. Insoluble fibre extractive pepsin-pancreatin digestibility differed between feed ingredients, and the single co-product test diets, and between the HF and LF mixed co-product diets. Fibre digestibility depended on both the origin and enzyme, with interaction, whereby carbohydrases expressed similar low (0.04-0.05) insoluble fibre digestibility for maize cob, moderate (0.12) digestibility for wheat bran and brewer's grain, with inferior Roxazyme G2 digestibility for maize hominy chop (0.02 vs 0.10) and meal (0.04 vs 0.16), dehulled soybean meal (0.02 vs 0.17), lucerne hay (0.08 vs 0.18), and soybean hulls (0.05 vs 0.33). Co-product-enzyme affinities were expressed in single fibre diets. Low Roxazyme-basal fibre affinity limited its comparative single co-product (0.03-0.07 vs 0.16-0.22) HF (0.07 vs 0.17) and LF (0.4 vs 0.20) dietary fibre digestibility. Screening for HF/LF did not affect enzymatic digestion, though enzyme combination increased HF, but not LF digestibility. Gas and short chain fatty acid production predicted fermentability proportionately in the declining order of dehulled soybean ≥ maize ≥ soy hulls ≥ maize hominy chop > wheat bran >lucerne hay ≥ brewer's grain = maize cob. Induced HF and LF contrast was significant. Co-product fibre enrichment decreased fermentability for all except the soy hull and HF diets. Cereal fibre yielded proportionately less acetate, with more propionate and butyrate, and a greater butyrate shift for maize fibre. The HF fibre induced more ACE and less butyrate. Biomarkers of deleterious proteolytic fermentation were high for lucerne (isobutyrate) and soy hulls (iso-valerate). In conclusion, high-level and fermentation based co-product feed dilution into maize-soybean growing pig diets altered enzymatic insoluble fibre hydrolysis and fermentation in relation to botanical origin. Roxazyme expressed weak hydrolytic potency on maize and soybean insoluble fibre.

In the poultry industry, growing concern about health risks is tightening regulations on the use of dietary antibiotic growth promoters (AGPs), raising interest in safer substitutes. The study investigated the phytogenic effects of drinking-water supplemented apple cider vinegar (ACV) and garlic extract (GAE) on broilers. The study used 390 Ross 308 broiler chicks reared in a deep litter, open house, within 2.3 m2 pen partitions. Treatments were randomly allocated in 2 (sex) x 5 (additives) factorial experiment replicated three times. Chicks started (days 1–22) on the same antibiotic starter diet, followed by grower and finisher (29–42 days) phase antibiotic-free diets plus untreated drinking water (Negative control (NC), antibiotic free diet plus ACV treated drinking water (T1), antibiotic free diet plus GAE treated drinking water (T2), antibiotic free diet plus ACV + GAE treated drinking water (T3) or antibiotic diet plus untreated drinking water (positive control (PC). Males had higher (P < 0.05) feed intake than females in both growth phases. Birds on the PC gained more (P < 0.05) weight than others. Birds on the PC consumed more feed (P < 0.05) during the finisher phase than T1, T2 and the NC. Birds on the PC had a lower (P < 0.05) grower-phase FCR than others, though with lower (P < 0.05) FCR during the finisher phase for birds on T1 and T3. Across sex, birds on the PC had the higher (P < 0.05) percent spleen weight than birds on T1. Across the sexes, birds on the PC had smaller proventriculus (P < 0.05) than on NC, T1, T2 and T3. Across the sexes, birds on the PC had lower (P < 0.05) gizzard weight than birds on the T2 and T3. Birds on the NC exhibited a lower dressing percentage (P < 0.05) than all other treatments. Meat pH was higher (P < 0.05) in males. In conclusion, in contrast to dietary antibiotics, except for increased dressing percentage, ACV and GAE did not improve broiler performance.

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