In this study, four experimental treatments were evaluated: (T1) alfalfa hay + concentrate, (50:50%, DM); (T2) alfalfa hay + Leucaena leucocephala + concentrate, (30:20:50%, DM); (T3) alfalfa hay + prickly pear + concentrate, (30:20:50%, DM); and (T4) alfalfa hay + Leucaena leucocephala + prickly pear + concentrate, (30:10:10:50%, DM). NH3-N concentrations in T2 and T4 decreased when replaced with alfalfa hay in 20 and 10%, respectively. Treatments did not affect the concentration of total volatile fatty acids (TVFA) between T3 and T4 (p > 0.05), while the concentrations among T1 and T2 were different (p < 0.05). T2 showed a reduction of 25.5% in the methane production when compared to T1 (p < 0.05). The lowest concentrations of protozoa were observed in T2 and T4, which contained Leucaena leucocephala (T2) and Leucaena leucocephala + prickly pear (T4) (p < 0.05). The highest concentration of total methanogens was recorded in T1 and was different in T2, T3, and T4 (p < 0.05). Leucaena leucocephala, at an inclusion percentage of 20%, decreased the methane when compared to T1, whereas prickly pear increased methane production in relation to T1.

Feed supplementation strategies are essential for optimizing cattle productivity, and the incorporation of non-conventional feed resources may reduce both production costs and environmental impact. This study evaluated the effects of pelletized protein concentrates (including Acacia farnesiana, A. schaffneri, and Agave duranguensis bagasse) on rumen fermentation parameters, microbial communities, and gas emissions. Fistulated bullocks received the concentrate daily, and ruminal contents were collected and filtered before and after supplementation to assess in vitro gas and methane production, pH, and microbial composition using high-throughput sequencing of 16S rRNA and mcrA amplicons. In addition, in situ degradability was evaluated during and after the supplementation period. Supplementation led to a significant (p < 0.05) reduction in degradability parameters and methane production, along with a marked decrease in the abundance of Methanobrevibacter and an increase in succinate-producing taxa. These effects were attributed to the enhanced levels of non-fiber carbohydrates, hemicellulose, crude protein, and the presence of bioactive secondary metabolites and methanol. Rumen microbiota composition was consistent with previously described core communities, and mcrA-based sequencing proved to be a valuable tool for targeted methanogen detection. Overall, the inclusion of non-conventional ingredients in protein concentrates may improve ruminal fermentation efficiency and contribute to methane mitigation in ruminants, although further in vivo trials on a larger scale are recommended.

In this study, four experimental treatments were evaluated: (T1) alfalfa hay + concentrate, (50:50%, DM); (T2) alfalfa hay + Leucaena leucocephala + concentrate, (30:20:50%, DM); (T3) alfalfa hay + prickly pear + concentrate, (30:20:50%, DM); and (T4) alfalfa hay + Leucaena leucocephala + prickly pear + concentrate, (30:10:10:50%, DM). NH3-N concentrations in T2 and T4 decreased when replaced alfalfa hay in 20 and 10 %, respectively. Treatments did not affect the concentration of total volatile fatty acids (TVFA) between T3 and T4 (p>0.05); while the concentrations among T1 and T2 were different (P<0.05). T2 showed a reduction of 25.5 % in the methane production when compared to T1(p < 0.05).The lowest concentrations of protozoa were observed in T2 and T4, which contained Leucaena leucocephala (T2) and Leucaena leucocephala + prickly pear (T4) (p<0.05). The highest concentration of total methanogens was recorded in T1 and were different to T2, T3 and T4 (p<0.05). Leucaena leucocephala at a inclusion percentage of 20 % decreased the methane when compared to T1; whereas prickly pear there was not a positive effect the methane production.

Livestock production has widely contributed to increase global production of greenhouse gases (GHG), mostly through digestive fermentation in ruminants. Moreover, emissions derived from livestock are estimated over 14% of the total anthropogenic GHG emissions to atmosphere. In addition, methane emitted from ruminal enteric fermentation is responsible for 25% of the total global methane emissions, which turns livestock activity into a main promoter of the climate change effect. However, these emissions may be diminished by modifying livestock diets through alterations in forage-concentrate ratios, the supplementation of feed additives, and the inclusion of alternative feedstuffs not commonly used as forage and protein sources in farm animal feeding. Additionally, the use of nonconventional feedstuffs is highly recommended since their production does not compete with human feeding and may provide metabolites used as methanogenesis suppressors. Likewise, agricultural by-products should be considered as potential feedstuffs for animal production by increasing the livestock efficiency and reducing the energy losses due to methane synthesis.

Background: The use of non-conventional food sources is a key element in facing the current problems derived from climate change and food shortages that demand the establishment of new sustainable feeding systems for ruminants. Moreover, densification methods like pelleting constitute a way to improve the quality and acceptability as well as to facilitate the handling of supplements. The objective of this study was to evaluate Huizache leaves and agave bagasse incorporated into granulated and pelletized concentrates and their effects on methane production and in vitro fermentation patterns in ruminant diets. Methods: A protein concentrate granulated and pelletized containing Huizache leaves and agave bagasse were mixed with a high-quality forage (alfalfa hay) using a 2×3 factorial arrangement with a total of six treatments. In each treatment were determined crude protein, carbohydrates, in vitro digestibility, in vitro gas, methane, carbon dioxide, volatile fatty acids, ammoniacal nitrogen and microbial nitrogen. The variables were submitted to an analysis of variance using the procedure MIXED SAS and statistical differences were declared at P less than 0.05. Result: There was an interaction (P less than 0.01) between concentrate source (granulated vs pelleted) and relation (alfalfa hay + concentrate source) on maximum gas production “A” (P less than 0.05). Also, there was an interaction between concentrate source (granulated vs pelleted) and relation (alfalfa hay: concentrated) on microbial nitrogen production (P less than 0.05). The microbial nitrogen production increased in 55 % with pelleted concentrate in relation to granulated concentrate (P less than 0.05).

Several strategies have been used to improve fat deposition and fatty acids composition; however, most of them are focused on reducing saturated fatty acids by increasing the content polyunsaturated acids. This study aimed to evaluate performance, carcass traits and fatty acids composition in the intramuscular fat of steers. Forty crossbred yearling steers (260 ± 5.9 kg LW) were supplemented with four levels of a glucogenic substrate: 0, 20, 40 and 60 g/d (T1, T2, T3 and T4, respectively). Animals were slaughtered after feeding trial, carcass traits and intramuscular fat samples were obtained. Final weight (FW) and average daily gain (ADG) increased with supplementation (p< 0.05); however, dry matter intake decreased in T2 (p< 0.05). Hot carcass weight, area rib eye and rib fat thickness increased with supplementation (p< 0.05). Likewise, saturated, monounsaturated and polyunsaturated fatty acids contents increased with supplementation of 60 g of glucogenic substrate (T3) versus T1 (p< 0.05). Additionally, Ω6/Ω3 ratio was different between treatments (p< .05). This ratio increased 20% with the addition of 20 g of glucogenic substrate compared to T1. Supplementation with 40 g/d of glucogenic substrate may improve fat deposition and fatty acids composition in intramuscular fat as well as enhance performance and carcass traits of feedlot cattle.