Nutritional performance and metabolic characteristics of cattle fed tropical forages with protein and starch supplementation.

Effects of protein supplementation, with and without starch supplementation, on nutritional performance and metabolic characteristics of cattle fed low- and medium-quality tropical forages were evaluated using 4 cannulated steers distributed according to a 4 × 4 Latin square. Experimental periods were divided into two subperiods. In the first subperiod, two animals received low-quality hay and two animals received medium-quality. Supplementation schemes were evaluated in the second subperiod: low-quality hay with protein (300 g of crude protein - CP/d); low-quality hay with protein (300 g CP/d) and starch (225 g/d); medium-quality hay with protein (300 g CP/d); and medium-quality hay with protein (300 g CP/d) and starch (225 g/d) supplementation. Without supplementation, medium-quality forage provided higher intake, digestibility, nitrogen balance (NB) and efficiency of nitrogen utilization (EFNU). Comparing subperiods, supply of supplements depressed medium-quality forage intake, but did not affect low-quality forage intake. Supplementation increased NB, EFNU and serum concentration of IGF1 in animals fed low-quality forage. Protein supplementation increases nitrogen retention in animals, an effect attributed mainly to anabolic stimuli. However, this effect is more prominent when animals are fed low-quality forages. No positive impact on animal metabolism was obtained with combination of supplemental protein and starch.

Evaluation of days of total collection and use of internal markers in nutritional trials with small ruminants.

Two experiments were conducted to evaluate the number of days required for total fecal collection and the viability of using the indigestible dry matter (iDM), indigestible neutral detergent fiber (iNDF), and indigestible acid detergent fiber (iADF) internal markers to determine the fecal excretion of dry matter (FEDM) and digestibility in nutritional trials with small ruminants. Eight sheep in the first experiment and eight goats in the second experiment were distributed into two 4 × 4 Latin square designs. There were no significant differences between days of total fecal collection for FEDM; digestibility of dry matter (DM), organic matter (OM), crude protein (CP), ether extract (EE), neutral detergent fiber corrected for ash and protein (NDFap), and non-fibrous carbohydrates corrected for ash and protein (NFCap); and total digestible nutrients (TDN) in both species. The results suggest that only 1 day of total collection is sufficient to obtain the FEDM and the digestibility of the nutritional components in sheep and goats. The markers are efficient in determining fecal production and digestibility in these animal species.

Intake and ingestive behavior in lambs fed low-digestibility forages.

Ingestive behavior of lambs fed diets consisting of fresh sugarcane with urea, bagasse treated with calcium oxide, and urea ammoniated sugarcane bagasse supplemented with concentrate mixture in 50:50 ratio were evaluated. For this, 34 wethers Santa Inês in their growing phase, with an average age of 3.0 ± 0.6 months and a mean initial live weight of 17.8± 5.2 kg were used. The animals were distributed in a completely randomized design and subjected to visual observation periods of 5 days, for 24 h a day, during the experimental period. Dry matter (DM) intake and intake efficiency of DM were higher (P < 0.05) for animals receiving fresh sugarcane with urea. The animals which were fed with bagasse treated with calcium oxide had higher (P < 0.05) consumption of neutral detergent fiber, longer feeding and chewing time (P < 0.05), and shorter (P < 0.05) idling time. The time spent on chewing the ruminal bolus did not differ from one diet to the other (P > 0.05). Grams of dry matter per ruminated bolus were similar among animals fed with fresh sugarcane and ammoniated bagasse (P > 0.05) but lower (P < 0.05) in animals fed with bagasse treated with calcium oxide. Rumination efficiency values, in grams of dry matter per hour, and grams of neutral detergent fiber per hour for all three diets were similar (P > 0.05) to those found for feeding efficiency. The number of feeding and rumination periods was not affected (P > 0.05) by diet. Based on the intake and ingestive behavior responses, the fresh sugarcane with urea compared to bagasse treated with calcium oxide and ammoniated bagasse was found to be the better alternative feed for use in lamb diets.