The objective of this study was to determine the variability in nutritive value for ruminants of tomato pomace (TP) samples and analyze its effect on in vitro fermentation when it was included in a high-concentrate diet. Twelve TP samples were obtained from two processing plants at weekly intervals and analyzed for chemical composition, in vitro rumen fermentation, and intestinal digestibility. The chemical composition of TP did not differ between processing plants and only slight variations were observed among sampling times. Tomato pomace had a low dry matter content (<300 g/kg), a high content of neutral detergent fiber, crude protein, and ether extract (572, 160, and 82.7 g/kg dry matter on average, respectively), and was rapidly fermented in the rumen. Protein degradability at 16 h in situ incubation was 510 g/kg and in vitro intestinal digestibility of protein was low (430–475 g/kg). Replacing soybean meal and barley straw by dried TP increased the in vitro fermentation rate and the production of volatile fatty acids and reduced NH₃-N concentrations without affecting CH₄. In summary, TP samples showed little variability in nutritive value over sampling time and TP of up to 180 g/kg could be included in high-concentrate diets without negatively affecting rumen fermentation.

The objective of this study was to evaluate the effect of replacing cereals and protein concentrates in a high-cereal concentrate (control) for light lambs with corn distiller’s dried grains with solubles (DDGS; 18%), dried citrus pulp (DCP; 18%), and exhausted olive cake (EOC; 8%) in a byproduct (BYP) concentrate on growth performance, digestibility, ruminal fermentation, and plasma metabolites. Two homogeneous groups of Lacaune lambs (13.8 kg ± 0.25 kg) were fed one of each concentrates and barley straw ad libitum until reaching about 26 kg body weight. There were no differences between groups on feed intake, average daily gain, or feed conversion ratio, but the control diet had greater (p < 0.001) dry matter digestibility. Diet had no effect on post-mortem ruminal pH and total volatile fatty acid concentrations and profile, but NH₃-N concentrations were lower (p = 0.003) for the BYP-fed group compared with the control one. However, plasma concentrations of amino acids, total proteins, urea, and hepatic enzymes were not affected by the diet. In conclusion, 44% of feed ingredients in the concentrate for light lambs can be replaced with a mixture of corn DDGS, DCP, and EOC without negatively affecting growing performance and animal health.

The objective of this study was to analyze the chemical composition, in vitro ruminal fermentation, and intestinal digestibility of discarded samples of four Brassica vegetables: Brussels sprouts (BS), white cabbage, Savoy cabbage, and red cabbage, and to assess the effects of including increasing amounts of BS in the concentrate of a dairy sheep diet on in vitro fermentation, CH₄ production, and in situ degradation of the diets. All cabbages had low dry matter content (DM; <16.5%), but their DM had high crude protein (19.5–24.8%) and sugars (27.2–41.4%) content and low neutral detergent fiber (17.5–28%) and was rapidly and extensively fermented in the rumen. Rumen degradability of protein at 12 h of in situ incubation was greater than 91.5% for all cabbages, and in vitro intestinal digestibility of protein ranged from 61.4 to 90.2%. Replacing barley, corn, and soybean meal by 24% of dried BS in the concentrate of a diet for dairy sheep (40:60 alfalfa hay:concentrate) increased in vitro diet fermentation and in situ degradability of DM and protein, and reduced in vitro CH₄/total volatile fatty acid ratio. In vivo trials are necessary to confirm these results.

The potential of broccoli wastes (florets and stems) as ruminant feed was analyzed using in vitro and in situ techniques. Both stems and florets had high moisture content (90.6 and 86.1%, respectively), but the stems contained (% dry matter) lower levels (p < 0.05) of crude protein (CP; 23.2 vs. 30.8%) and ether extract (2.91 vs. 6.15%) and tended to have greater sugars content (p = 0.071; 33.4 vs. 19.6%) than florets. Stems had greater in vitro dry matter rumen degradability (45.3%; 24 h incubation) and lower in vitro CP intestinal digestibility (82.7%) compared with florets (42.2 and 90.1%, respectively). Rumen degradability of protein was high (<85%) for both fractions. In a second experiment, diets including different proportions of broccoli were formulated and fermented in vitro. The replacement of 24% of conventional feeds (wheat, soybean meal and wheat bran) in a concentrate by dried broccoli increased the amount of organic matter fermented in vitro and the NH₃-N concentrations of a mixed diet including 40% of the concentrate. Including dried broccoli in the diet produced only small modifications in the volatile fatty acid profile and did not affect CH₄ emission.

Twelve Murciano-Granadina dairy goats were divided into two homogeneous groups, which were fed either a control diet composed of 40% alfalfa hay and 60% concentrate or a diet based on 40% alfalfa hay, 40% concentrate and 20% multinutrient blocks, including 14.8% avocado pulp and peels (APP). Total dry matter (DM) intake was similar (p = 0.709) for both diets, but APP-fed goats had lower (p = 0.024) concentrate intake and tended (p = 0.063) to have lower fat intake compared with those fed the control diet. The average intake of blocks was low (66.4 g DM/d), which was attributed to avocado lipids oxidation and rancidity. Neither milk yield (p = 0,921) nor the efficiency of energy and nitrogen use were affected (p = 0.909 and 0. 840, respectively) by the diet, but milk fat tended to be greater (p = 0.057) in the APP-fed goats compared with the animals fed the control diet. Other milk components were similar (p ≥ 0.110) for both diets, and only subtle changes in the milk fatty acid profile were observed. In summary, the intake of blocks containing avocado wastes by dairy goats was low probably due to avocado lipids oxidation causing off-flavors and reduced palatability.

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.