What is the digestibility and caloric value of different botanical parts in corn residue to cattle?1.

Two experiments were conducted to measure rates of ruminal disappearance, and energy and nutrient availability and N balance among cows fed corn husks, leaves, or stalks. Ruminal disappearance was estimated after incubation of polyester bags containing husks, leaves or stalks in 2 separate ruminally cannulated cows in a completely randomized design. Organic matter (OM) that initially disappeared was greatest for stalks and least for husks and leaves (P < 0.01), but amounts of NDF that initially disappeared was greatest for husks, intermediate for stalks, and least for leaves (P < 0.01). Amounts of DM and OM that slowly disappeared were greatest in husks, intermediate in leaves, and least in stalks (P < 0.01). However, amounts of NDF that slowly disappeared were greatest in leaves, intermediate in husks, and least in stalks (P < 0.01). Rate of DM and OM disappearance was greater for leaves, intermediate for husks and least for stalks, but rate of NDF disappearance was greatest for stalks, intermediate for leaves, and least for husks (P < 0.01). Energy and nutrient availability in husks, leaves, or stalks were measured by feeding ruminally cannulated cows husk-, leaf-, or stalk-based diets in a replicated Latin square. Digestible energy lost as methane was less (P = 0.02) when cows were fed leaves in comparison to husks or stalks, and metabolizable energy (Mcal/kg DM) was greater (P = 0.03) when cows were fed husks and leaves compared with stalks. Heat production (Mcal/d) was not different (P = 0.74) between husks, leaves, or stalks; however, amounts of heat produced as a proportion of digestible energy intake were less (P = 0.05) among cows fed leaves in comparison to stalks or husks. Subsequently, there was a tendency (P = 0.06) for net energy available for maintenance from leaves (1.42 Mcal/kg DM) to be greater than stalks (0.91 Mcal/kg DM), and husks (1.30 Mcal/kg DM) were intermediate. Nitrogen balance was greater when cows were fed leaves, intermediate for husks, and least for stalks (P = 0.01). Total tract digestion of NDF was greater (P < 0.01) for husks and leaves compared with stalks. Husks had greater (P = 0.04) OM digestibility in comparison to stalks, and leaves were intermediate. Apparently, greater production of methane from husks in comparison to leaves limited amounts of energy available for maintenance from husks even though total-tract nutrient digestion was greatest when cows were fed husks or leaves.

Estimates of diet selection in cattle grazing cornstalk residues by measurement of chemical composition and near infrared reflectance spectroscopy of diet samples collected by ruminal evacuation.

Six ruminally cannulated cows (570 ± 73 kg) fed corn residues were placed in a 6 × 6 Latin square to evaluate predictions of diet composition from ruminally collected diet samples. After complete ruminal evacuation, cows were fed 1-kg meals (dry matter [DM]-basis) containing different combinations of cornstalk and leaf and husk (LH) residues in ratios of 0:100, 20:80, 40:60, 60:40, 80:20, and 100:0. Diet samples from each meal were collected by removal of ruminal contents after 1-h and were either unrinsed, hand-rinsed or machine-rinsed to evaluate effects of endogenous compounds on predictions of diet composition. Diet samples were analyzed for neutral (NDF) and acid (ADF) detergent fiber, acid detergent insoluble ash (ADIA), acid detergent lignin (ADL), crude protein (CP), and near infrared reflectance spectroscopy (NIRS) to calculate diet composition. Rinsing type increased NDF and ADF content and decreased ADIA and CP content of diet samples (P < 0.01). Rinsing tended to increase (P < 0.06) ADL content of diet samples. Differences in concentration between cornstalk and LH residues within each chemical component were standardized by calculating a coefficient of variation (CV). Accuracy and precision of estimates of diet composition were analyzed by regressing predicted diet composition and known diet composition. Predictions of diet composition were improved by increasing differences in concentration of chemical components between cornstalk and LH residues up to a CV of 22.6 ± 5.4%. Predictions of diet composition from unrinsed ADIA and machine-rinsed NIRS had the greatest accuracy (slope = 0.98 and 0.95, respectively) and large coefficients of determination (r2 = 0.86 and 0.74, respectively). Subsequently, a field study (Exp. 2) was performed to evaluate predictions of diet composition in cattle (646 ± 89 kg) grazing corn residue. Five cows were placed in 1 of 10 paddocks and allowed to graze continuously or to strip-graze corn residues. Predictions of diet composition from ADIA, ADL, and NIRS did not differ (P = 0.99), and estimates of cornstalk intake tended to be greater (P = 0.09) in strip-grazed compared to continuously grazed cows. These data indicate that diet composition can be predicted by chemical components or NIRS by ruminal collection of diet samples among cattle grazing corn residues.

Influence of distiller's dried grains with solubles on ram lamb growth and reproductive traits.

The hypothesis of this experiment was that increasing the inclusion level of distiller's dried grains with solubles (DDGS) in the diets would decrease semen quality but have no negative effects on growth performance. Following the removal of DDGS from the diet, it was hypothesized that the ram lambs would recover and become reproductively sound, independent of treatment. To test this hypothesis, Suffolk and Hampshire ram lambs (n = 112) were allocated to 4 treatments (n = 4 pens per treatment; 7 rams per pen) in a completely randomized design. Dietary treatments were 60% corn, 25% oats, and 15% commercial lamb pellet (CON), 15% of the ration as DDGS substituted for corn (% DM basis; 15DDGS), 30% of the ration as DDGS substituted for corn (% DM basis; 30DDGS), and 45% of the ration as DDGS substituted for corn (% DM basis; 45DDGS). Lambs were fed for 112 d on their respective treatment, after which they were placed on the CON ration until day 168. Lambs were weighed on consecutive d at the beginning (days 0 and 1) and end (days 167 and 168) of the study. Scrotal circumference was measured on all lambs on days 84, 112, 140, and 168. Semen samples were collected on a subset of 64 rams (4 rams per pen) to evaluate semen quality on days 84, 112, 140, and 168. Blood samples were collected on the same subset of rams every 14 d throughout the study. A quadratic effect on BW on day 112 and overall BW (P = 0.03 and P = 0.005, respectively), ADG on day 112 and overall ADG (P = 0.02 and P = 0.02, respectively), DMI (P = 0.007) on day 112, and a cubic effect (P = 0.05) for overall G:F were observed. Overall and day 168 scrotal circumference had a quadratic (P = 0.05) response. A linear increase in spermatozoa concentration on day 168 was observed (P = 0.03) as DDGS concentration increased in the treatment diets, although rams in this stage of the study were no longer receiving DDGS. Overall, testosterone concentrations exhibited a linear decrease (P = 0.005) as DDGS increased in the diet. The linear increase (P = 0.04) on day 168 in morphologically normal sperm as DDGS increased in the diets indicated that all rams, regardless of treatment, would have passed a reproductive soundness exam. In the current study, no negative effects were observed in lamb feedlot or reproductive traits due to increasing DDGS in the diet, indicating that DDGS may be included at levels up to 45% of growing lamb diets.