Comparison of acid-detergent lignin,alkaline-peroxide lignin,and acid-detergent insoluble ash as internal markers for predicting fecal output and digestibility by cattle offered bermudagrass hays of varying nutrient composition

Background： The potential for acid-detergent insoluble ash （ADIA）, alkaline-peroxide lignin （APL）, and acid-detergent lignin （ADL） to predict fecal output （FO） and dry matter digestibility （DMD） by cattle offered bermudagrass [Cynodon doctylon （L） Pers.] hays of different qualities was evaluated. Eight ruminally cannulated cows （594 ± 35.5 kg） were allocated randomly to 4 hay diets： low （L）, medium low （ML）, medium high （MH）, and high （H） crude protein （CP） concentration （79, 111,131, and 164 g CP/kg on a DM basis, respectively）. Diets were offered in 3 periods with 2 diet replicates per period and were rotated across cows between periods. Cows were individually fed 20 g DM/kg of body weight in equal feedings at 08：00 and 16：00 h for a 10-d adaptation followed by a 5-d total fecal collection. Actual DM intake （DMI）, DMD, and FO were determined based on hay offered, ort, and feces excreted. These components were then analyzed for ADL, APL, and ADIA concentration to determine marker recovery and marker-based estimates of FO and DMD. Results： Forage DMI was affected by diet （P = 0.02）, and DMI from MH and H was greater （P 〈 0.05） than from L. Apparent DMD tended （P = 0.08） to differ among diets while FO （P = 0.20） was not affected by diet treatments. Average ADL recovery （1.16） was greater （P 〈 0.05） than that of ADIA （1.03） and APL （1.06）, but ADIA and APL did not differ （P = 0.42）. Estimates of FO and DMD derived using APL and ADIA were not different （P≥0.05） from total fecal collection while those using ADL differed （P 〈 0.05）. There was no diet by marker interaction （P≥ 0.22） for either FO or DMD. Conclusion： Acid-detergent insoluble ash and APL accurately predicted FO and DMD of cattle fed bermudagrass hay of varying nutrient composition. These internal markers may facilitate studies involving large numbers of animals and forages. Results from such studies may be used to develop improved equations to predict energy values of forages based on the relationship of dietary components to digestibility across a wide range of forages.

White (<i>Trifolium repens</i>L.) and Arrowleaf (<i>Trifolium vesiculosum</i>Savi) Clover Emergence in Varying Loblolly Pine (<i>Pinus taeda</i>L.) Tree Alley Spacings

Agroforestry systems have the potential to provide year-long income opportunities via the integrated forage or crop, timber, and livestock. Legumes are an attractive alternative option during the growing season when more traditional forages may not be as productive. The objective of this study was to test the establishment of arrowleaf and white clover grown under varying pine tree alley widths. In 2011, existing forage was removed in 15-yr old loblolly pine tree row alleys of different widths (3.7, 4.9, 7.3, and 9.8 m), including an open area. Arrowleaf, as an annual, was replanted in 2012. Seedlings were counted twice/year, while dry matter was measured three times/year. Photosynthetically active radiation (PAR) was measured in all alley widths to compare light penetration through the canopy. Hot and dry conditions occurred throughout 2012, affecting results. In 2012 and 2013, the greatest PAR for most treatments was observed in June. Seedling counts for all treatments were greatest immediately after establishment, and gradually declined throughout the course of the study. Dry matter yields increased throughout the growing season, and were greatest in arrowleaf clover in the open area on all measurement dates;however, increased weed pressure and repeated flooding affected yields. This study demonstrated that clover establishment in shady wooded areas is possible, but only under suitable environmental conditions.

Diurnal variation in fecal concentrations of acid-detergent insoluble ash and alkaline-peroxide lignin from cattle fed bermudagrass hays of varying nutrient content

Background： The effect of time of fecal sampling on the accuracy of acid-detergent insoluble ash （ADIA） and alkaline-peroxide lignin （APL） for the prediction of fecal output （FO） in cattle was evaluated. Eight ruminally cannulated cows （594 _＋ 35.5 kg） were allocated randomly to 4 bermudagrass [Cynodon dactylon （L.） Pers.] hay diets markedly different in crude protein concentration （79-164 g/kg） with 2 replicates per diet for 3 periods. Cows were offered hay individually at 20 g DM/kg of body weight daily in equal feedings at 08：00 and 16：00 h for a 10-d adaptation period followed by 5-d of total fecal collection. Fecal grab samples also were taken each day during the fecal collection period at 06：00, 12：00, 18：00, and 24：00 h either directly from the rectum or from freshly voided feces. Samples were composited within cow and time across the 5 d total fecal collection period. Additionally, forage, ort, and fecal samples were analyzed for concentrations of APL and ADIA. Results： Fecal concentrations of ADIA and APL were not affected by sampling time （P 〉 0.22）, even though diet affected （P 〈 0.01） fecal ADIA and APL concentrations. There were no diet x sampling time interactions （P ≥ 0.60）. Estimates of FO and dry matter digestibility （DMD） from ADIA and APL were not affected （P 〉 0.16） by sampling time or the diet x sampling time interaction （P 〉 0.74）. Estimates of FO and DMD from markers from different sampling times or all different combinations of sampling time were not different （P 〉 0.72） from those of total collection among internal markers. Conclusion： Little variation in concentrations of ADIA and APL in daily fecal excretion across time increases flexibility in fecal grab sampling schedules for predicting FO and DMD.