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 NH3-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.

Ruminants have a low efficiency of nitrogen (N) utilization that has negative implications for animal production and the environment, but reducing the ruminal degradation of protein can help to reduce N losses. The objective of this study was to evaluate the inclusion of sunflower meal (SM) and sunflower seed (SS) protected against ruminal degradation in high-cereal diets on in vitro ruminal fermentation and CH production. Samples of SS and SM were sprayed with a solution of malic acid 1 M (400 ml/kg sample) and dried at 150°C for 1 hr as a protective treatment. Four diets were formulated to contain either 13 (low) or 17 (high) g of crude protein (CP)/100 g dry matter (DM), and included SM and SS either untreated (13CON and 17CON diets) or treated as before described (13TR and 17TR diets). Diets were incubated in vitro with rumen fluid from sheep for 8 and 24 hr. The treatment did not affect (p ≥ 0.57) total volatile fatty acid (VFA) production at any incubation time, but it reduced (p < 0.05) NH -N concentrations by 19.2 and 12.5% at 8 and 24 hr respectively. Both CH production and CH /VFA ratio were lower (p < 0.02) in TR than in CON diets at 8 hr, but differences disappeared (p > 0.05) at 24 hr. The treatment increased the molar proportion of propionate (p = 0.001) and reduced that of isovalerate (p = 0.03) at 8 hr compared with CON diets, but only a reduction of isovalerate proportion (p = 0.03) was detected at 24 hr. There were no treatment x crude protein level interactions (p > 0.05) in any parameter, but high-protein diets had greater NH -N concentrations (p < 0.001) and lower VFA production (p < 0.001) than low-protein diets at 24 hr. The treatment reduced protein degradation, and CH production was decreased by 4.6 and 10.8% for low- and high-protein diets, respectively, at short incubation times without affecting VFA production, thus improving fermentation efficiency and decreasing polluting emissions.

Simple Summary: One of the main objectives of animal nutrition is to optimize the production of the animals in order to obtain good-quality products, but decreasing the environmental pollution caused by livestock production has also become a priority in the last years. Compared to other farm animals, ruminants have low N utilization efficiency that is mainly due to the inefficient use of nitrogen (N) in the rumen and a large portion of the ingested N is excreted causing environmental problems such as water and soil eutrophication. In this study we analyzed the influence of feeding sunflower seeds (SS) and meal (SM) subjected to a combined malic acid-heat treatment (MAH) on carcass characteristics and meat composition and fatty acid profile of growing lambs. The MAH treatment was applied to reduce ruminal degradation of SS and SM protein and therefore N losses. Compared to control-fed lambs, animals fed the treated SS and SM had increased dorsal fat thickness and yellowness and chromaticity of the Rectus abdominis muscle, which might be beneficial for consumers' acceptance as they associate a bright meat color with meat freshness and quality. However, there were no differences between groups in meat chemical composition and fatty acid profile. Abstract:The objective of the study was to assess the effects of feeding sunflower meal (SM) and seeds (SS) protected against rumen degradation on carcass characteristics and composition and fatty acid (FA) profile of lamb meat. The protection of SM and SS was achieved by treating both feeds with malic acid at 150 • C for 2 h (MAH treatment) and in a previous study this treatment was shown to decrease ruminal degradability of protein of both feeds and fat degradability of SS. Two homogeneous groups of 12 lambs each were fed ad libitum high-cereal concentrates and cereal straw from 14 to 26 kg of body weight. The two concentrates differed only in the treatment SM and SS, which were included either untreated (control) or MAH treated. The MAH-fed lambs had greater thickness of dorsal fat (p = 0.016) and greater (p ≤ 0.016) values of the color parameters a* (redness) and C* (chromaticity) of the Rectus abdominis muscle. However, there were no differences in carcass measurements and in water-holding capacity, chemical composition, pH, color, or fatty acid of Longissimus muscle. In summary, the MAH treatment resulted in only subtle changes in meat composition and quality.

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