Effects of Feeding Rumen-Protected Sunflower Seed and Meal Protein on Feed Intake, Diet Digestibility, Ruminal, Cecal Fermentation, and Growth Performance of Lambs

SIMPLE SUMMARY: Due to inefficient use of nitrogen (N) in rumen, ruminants have a low efficiency of N utilization. A large part of ingested N is excreted into the environment without being used by animals. The objective of this study was to analyze the efficacy of a treatment combining malic acid and heating (MAH) to protect the protein in sunflower seeds (SS) and meal (SM) against rumen degradation and to improve the growth of lambs. Two high-cereal concentrates, either including untreated or MAH-treated SS and SM, were fed to two homogeneous groups of lambs. Further, feed intake, diet digestibility, and lamb growth from 14 to 26 kg body weight were assessed. An in vitro trial indicated that the MAH-treatment modified the rumen fermentation pattern of both SS and SM, and it reduced the NH(3)-N concentrations for SM. However, there were no significant effects of the MAH-treatment on feed intake, diet digestibility or growth of lambs. The hot carcasses of the lambs fed the MAH-treated concentrate were 7.9% heavier but not statistically different to those of the untreated group. In conclusion, under the conditions of the present study the MAH treatment did not improve the growth performance of lambs. ABSTRACT: The objective of this study was to analyze the efficacy of a treatment (MAH) of sunflower seed (SS) and meal (SM) with a malic acid solution (1 M; 400 mL/kg) and heating (150 °C, 2 h) to protect protein against rumen degradation and to improve the growth of lambs. Two homogeneous groups of 12 Lacaune lambs each (14.2 ± 0.35 kg body weight) were fed either a concentrate including untreated SS and SM or a concentrate with MAH-treated SS and SM. Lambs were fed concentrate and barley straw ad libitum for 40 days (about 26 kg body weight); feed intake and growth of lambs were recorded; blood samples were taken on days 0, 20, and the slaughter day for analysis of urea-N and amino acid-N; diet digestibility was determined; and ruminal and cecal samples were collected after slaughter. The in vitro incubation of both concentrates with sheep ruminal fluid for 12 h showed that the MAH-treatment tended to reduce NH(3)-N concentrations and increased propionate production. However, there were no differences (p > 0.05) between groups in any of the tested variables in the in vivo trial.