G. M. Hill

Effect of enzyme or microbial treatment of bermudagrass forages before ensiling on cell wall composition, end products of silage fermentation and in situ digestion kinetics

Tifton 85 bermudagrass (T85) and Coastal bermudagrass (CBG) established on adjacent plots and managed similarly were harvested after 3 or 6 weeks of regrowth and used to investigate the effects of fibrolytic enzymes or microbial inoculant treatment before ensiling on nutrient composition and recovery, cell wall chemistry and digestion. Prior to ensiling T85 had higher concentrations of neutral detergent fiber (NDF) and acid detergent fiber (ADF), similar concentrations of total lignin, and greater (p < 0.05) in vitro and in situ dry matter (DM) and NDF disappearances when compared with CBG. Coastal bermudgrass had higher (p < 0.05) concentrations of acid-insoluble lignin and ether-linked ferulic acid (monomers and dimers), and lower concentrations of glucose and mannose than T85. Treatment of bermudagrass forages with microbial inoculant decreased (p < 0.05) concentrations of NDF, hemicellulose, butyrate, lactate, cell walls and acid-insoluble lignin, and increased (p < 0.05) concentrations of ammonia, total volatile fatty acids (VFA) and acetate in silages. Treatment of bermudagrass forages with fibrolytic enzymes had no effect on silage fiber concentration, cell wall carbohydrate fraction or concentration of p-coumaric and ferulic acids, but increased the concentration of butyrate. Among silages, T85 had higher (p < 0.05) in vitro and in situ dry matter DM and NDF disappearance and higher (p < 0.05) potentially digestible fractions and smaller (p < 0.05) indigestible fractions of DM and NDF than CBG. Treatment of bermudagrass forages with fibrolytic enzymes had no effect on in vitro or in situ DM or NDF disappearance of silages. Treatment of bermudagrass forages with microbial inoculant increased in situ DM disappearance at 72 h of incubation (p < 0.10) and the potentially digestible fraction of DM (p < 0.05) of silages. Although treatment of bermudagrass forages with microbial inoculant had no effect on silage in vitro or in situ NDF disappearance at 48 h of incubation, it increased in situ NDF disappearance at 72 h (p < 0.05) and the potentially digestible fraction of NDF. It is concluded that the greater cellulose content of cell walls with the same or less lignin in T85, and the greater concentration of ether-linked ferulic acid in CBG explain the greater digestibility of T85 when compared with CBG at similar stages of maturity. Treatment of bermudagrass forage at ensiling with microbial inoculants may have more potential than extracts of fibrolytic enzymes in improving silage fiber digestion.

Peanut by-products fed to cattle

Peanut by-products supply substantial quantities of feedstuffs to beef cattle grown in the same region where peanuts are produced. Included in the list of products fed to cattle are peanuts and peanut meal, peanut skins, peanut hulls, peanut hay, and silages. Residual peanut hay is by far the most widely used peanut by-product fed to beef cattle, and if it is properly harvested with minimal leaf shatter, it is comparable to good-quality grass hays in nutrient content. Peanut skins are often included in small quantities in cattle and pet foods, supplying both protein and energy. High tannin content of peanut skins can cause severe performance depressions in beef cattle if peanut skins are included at levels higher than 10% of the diet, unless diets contain relatively high CP (above 15% CP), or additional N sources are added such as ammonia or urea. Because dairy cattle diets are often above 16% CP in the total dietary DM, peanut skins may increase milk production when added at levels up to 16% of the dry matter. Peanut hulls are effectively used as a roughage source at levels up to 20% of beef finishing diets, for bedding in dairy cattle loafing sheds (if tested and found to contain low aflatoxin levels), and in a variety of manufactured products. Peanut hulls are economically priced because of their quantity, their inherent high fiber, and low CP content, and they should not be fed as a primary feedstuffs for beef cattle. Peanut by-products are generally priced below other by-products, and they can be incorporated into a variety of supplements and diets for cow herds, growing-finishing cattle, and dairy cattle.

Effect of hay maturity, forage source, or neutral detergent fiber content on digestion of diets containing Tifton 85 bermudagrass and corn silage

Total mixed rations (TMRs) based on corn silage (30% DM) or Tifton 85 bermudagrass hay harvested at 3.5 and seven weeks of growth and with low or high neutral detergent fiber (NDF) content were used to study the effects of hay maturity, forage source, or level of dietary NDF on in situ digestion kinetics for TMRs. Among forages, NDF and lignin concentrations decreased in the order of: Tifton 85 bermudagrass harvested at seven weeks of growth, Tifton 85 bermudagrass harvested at 3.5 weeks of growth, and corn silage, while in vitro and in situ dry matter (DM) digestion showed the opposite trend. The extent of in situ NDF digestion decreased in the order of: Tifton 85 bermudagrass harvested at 3.5 weeks of growth, (60.1%), Tifton 85 bermudagrass harvested at seven weeks of growth (45.6%), and corn silage (42.5%). Increase in bermudagrass maturity decreased (P<0.01) in vitro NDF disappearance for TMRs at 48 h of incubation from 44.7 to 38.8%. Forage source or the level of dietary NDF had no effect on the extent of in situ DM digestion for TMRs. Increase in bermudagrass maturity decreased (P<0.05) the extent of in situ digestion of DM and NDF for TMRs. After fitting the nonlinear model to the disappearance data, the TMR in which corn silage was used as the forage source had higher (P<0.05) readily digestible fraction of DM than T85 based TMRs. Digestion profiles for 3.5 weeks bermudagrass based TMRs were similar to those of corn silage based TMR.

In vitro digestion kinetics of neutral detergent fiber extracted from Tifton 85 and Coastal bermudagrasses

Hays used to compare the digestion kinetics of neutral detergent fiber (NDF) were Tifton 85 bermudagrass (T85) harvested after 3.5 or 7 weeks of growth, a second cutting of T85 harvested after 3.5 weeks of regrowth, and Coastal bermudagrass (CBG) harvested after 4 weeks of growth. Neutral detergent fiber extracted from the hays was exposed to in vitro digestion and the digesta analyzed for their NDF content. The in vitro dry matter disappearance for the first (63.6%) and second (59.9%) cutting of 3.5-weeks old T85 was similar but higher than that for T85 harvested after 7 weeks of growth (48.7%) or CBG harvested after 4 weeks of growth (52.0%). In vitro NDF digestion at 72 h of incubation for T85 harvested at 3.5 week (74.5%) was similar to that of 3.5-weeks T85 regrowth (67.4%), but higher than that of CBG (63.7%) or 7-weeks T85 (53.7%). After fitting a nonlinear model to the data, T85 harvested at 3.5 week had a higher (P<0.05) potentially digestible fraction of NDF. Extraction of NDF from the hays increased the potentially digestible fraction of NDF. In summary, Tifton 85 bermudagrass harvested at 3.5 week had a higher NDF concentration, and higher NDF digestion than did Coastal bermudagrass harvested at 4 week.

ASAS Centennial Paper: Future needs of research and extension in forage utilization.

Forage-animal production agriculture is implementing infrastructure changes and management strategies to adjust to increased energy-related costs of fuel, feed grains, fertilizers, and seeds. The primary objectives of this position paper are to assess future research and extension scientific needs in forage utilization, financial support for the discipline, and changing status and number of scientists. A survey questionnaire returned from 25 land-grant universities in the eastern half of the United States rated the top 4 research needs as 1) pasture systems and efficiency of production; 2) interfacing with energy concerns; 3) forage cultivar evaluations and persistence; and 4) environment impacts. Plant-animal future research needs at 11 USDA-ARS regional locations are targeted at sustainable management and improved livestock performance, ecophysiology and ecology of grasslands, environment impacts, and improved technologies for nutritive value assessments. Extension scientists from 17 southern and northeastern states listed the top 3 needs as forage persistence, soil fertility and nutrient management, and pasture systems and efficiency of production. Grant funds currently provide more than 40% of land-grant university research and extension efforts in forage utilization, and scientists estimate that this support base will increase to 55 to 60% of the funding total by 2013. Reduced allocation of state and federal funding has contributed to a reduction in the number of full-time equivalent (FTE) scientists engaged in forage utilization research and extension activities. The current 25 state FTE conducting research number about 2.8 per state. This includes 10 states with >3, 11 states with <2, and 3 states with <1 FTE. Increased interest in cellulosic energy, climate change, and environmental impact may offer new opportunities for these FTE to participate in integrated cross-discipline research Extension programming, and technology transfer methods will change to accommodate reduced funding but with increasing numbers of novice, recreation-oriented landowners.

Pigeon peas as a supplement for lactating dairy cows fed corn silage-based diets

Holstein rumen-cannulated cows [n=7; initial body weight (BW) 640.56±71.43 kg] were fed a corn silage basal diet with 1 of 3 concentrates (C=control; P10=10% pigeon peas; P20=20% pigeon peas). Cows were randomly assigned to treatments in a replicated 3×3 Latin square and individually fed using Calan gates. Each experimental period was 21 d with 7 d for adaption and 14 d for sample collection. Ruminal fluid samples were taken the last day of each experimental period and analyzed for pH, ammonia, long-chain fatty acids, and volatile fatty acids (VFA). Consecutive a.m. and p.m. milk samples were taken during the last 2 wk of the 21-d period and analyzed for fat, protein, long-chain fatty acids, and somatic cell count. Dry matter intake (kg/d) was reduced during the second period and was greater for P10 diets. Milk protein was greater for cows fed P20 compared with P10. Energy-corrected milk was greater for cows fed the control diet compared with P10. Treatment had no effect on milk yield. Ruminal fluid pH decreased over sampling times; however, pH remained at or above 5.5. Diets did not affect ruminal fluid pH; however, pH was different for sampling periods. Ruminal ammonia decreased until 8h postfeeding at which time it peaked consistent with changes in ammonia concentrations that usually peak 3 to 5h postfeeding on diets high in plant proteins. Dietary treatments altered ruminal fluid VFA with reduced concentrations of acetate and greater concentrations of propionate for control diet, resulting in reduced acetate:propionate ratio. Isobutyrate exhibited an hour by treatment interaction, in which isobutyrate decreased until 8h postfeeding and then tended to be greater for P10 than for other treatments. Animals fed the P10 diet had greater concentrations of ruminal isovalerate. Ruminal cis-9,trans-11 and trans-10,cis-12 conjugated linoleic acid (CLA) isomers were not affected by dietary treatments. The P10 diet had greatest ruminal synthesis of cis-9,trans-11, but control cows had greatest ruminal synthesis of trans-10,cis-12. Milk CLA isomers were similar among treatments. Trends were observed for greater cis-9,trans-11 and trans-10,cis-12 for the P10 diet. Pigeon peas may be used as a protein supplement in dairy diets without affecting milk production, dry matter intake, or ruminal environment when they replace corn and soybean meal.