Llama and sheep ruminal fluid digestive capacity by in vitro gas production technique.

BACKGROUND: The in vitro gas production technique has been used to evaluate forage fermentation kinetics. However, individual and animal species variation can change fermentation patterns due to differences in ruminal environment and microbiota. The aim was to verify whether rumen inoculum (RI) of llama had superior intrinsic digestion capacity and reduced methane (CH4 ) production compared to sheep RI using fescue and paspalum hay as substrates. RESULTS: Dry and organic matter (OM) digestibility produced with llama RI tended to exceed that of sheep (P = 0.099 and 0.074, respectively) at 24 h of incubation. However, at 48 h, the sheep RI presented higher substrate digestibility and asymptotic value of gas production than that of llama (P < 0.010). CH4 production showed no differences between RI or substrates (P > 0.050). The NH3 -N and total volatile fatty acid concentrations were greater in the RI of llamas compared to those of sheep (P < 0.050). Acetate and butyrate proportions and acetate-to-propionate ratio were greater in the RI of llamas compared to those of sheep (P < 0.001) at 24 and 48 h. However, propionate proportion was greater in sheep compared with llama (P < 0.001). CONCLUSION: Llama RI tended to surpass that of sheep in dry and OM digestibility at 24 h of incubation, but sheep RI at 48 h presented a higher digestibility and gas production value than llama RI. No differences between the two species were detected for CH4 production. This study showed that llama RI did not perform better than sheep RI in digesting low-quality forages. © 2022 Society of Chemical Industry.

Pre-incubation of ruminal inocula to assess in vitro gas production and digestibility / Pré-incubação de inóculo ruminal para avaliação da produção de gases e digestibilidade in vitro

ABSTRACT: In vitro gas production techniques represent a valuable tool to describe the kinetics of ruminal degradation of food. However, the ruminal liquor used as a microbial inoculum has been a great source of variation and error. A standardization of this factor should contribute to assure the independence of food fermentation parameters from those of the inocula. In this research it was hypothesized that a controlled pre-incubation treatment of ruminal liquor could contribute to stabilize and homogenize the undigested residues of blanks and as a consequence, of the production of residual cumulative gas production (CGP). A pre-incubation (i.e. previous real incubation) of rumen inocula was developed with a simple substrate similar to the diet offered to donors at 1% w/v for 0, 1, 2 and 4 h (Control, Prei-1, Prei-2 and Prei-4 treatments respectively). Once the pre-incubation hours were completed, they were incubated with contrasting substrates and without substrate (i.e. blanks) in order to evaluate the CGP, in vitro digestibility of the DM and fermentation products. Although, the fermentative activity of the pre-incubated inoculums worked satisfactorily in the in vitro system, contrary to what was speculated, residues of the pre-incubation increased the variability and heterogeneity of variances among blanks. Consequently, it was concluded that the pre-incubations did not work to generate more homogeneous and less variable ruminal liquor for the in vitro gas production system.

RESUMO: Técnicas de produção de gás in vitro representam uma ferramenta valiosa para descrever a cinética de degradação ruminal dos alimentos. No entanto, o líquido ruminal utilizado como inóculo microbiano tem sido uma grande fonte de variação e erro. A padronização deste fator deve contribuir para garantir a independência dos parâmetros de fermentação dos alimentos a partir dos inóculos. Neste trabalho, hipotetizou-se que um tratamento controlado de pré-incubação do líquido ruminal poderia contribuir para estabilizar e homogeneizar os resíduos não digeridos dos brancos e, como conseqüência, da produção de produção cumulativa de gás residual (CGP). Uma pré-incubação (ou seja, incubação real prévia) dos inóculos do rúmen foi desenvolvida com um substrato simples semelhante à dieta oferecida aos doadores a 1% p/v por 0, 1, 2 e 4 h (Controle, Prei-1, Pré- 2 e Prei-4 tratamentos respectivamente). Uma vez completadas as horas de pré-incubação, elas foram incubadas com substratos contrastantes e sem substrato (ou seja, brancos) para avaliar o CGP, a digestibilidade in vitro da MS e os produtos de fermentação. Embora a atividade fermentativa dos inóculos pré-incubados tenha funcionado satisfatoriamente no sistema in vitro, ao contrário do que foi especulado, os resíduos da pré-incubação aumentaram a variabilidade e heterogeneidade das variâncias entre os brancos. Consequentemente, concluiu-se que as pré-incubações não funcionaram para gerar um líquido ruminal mais homogêneo e menos variável para o sistema de produção de gás in vitro.

In vitro digestion of fresh alfalfa under different conditions of ruminal pH.

BACKGROUND: Relatively low ruminal pH values have been frequently registered in dairy cows grazing alfalfa, which can be involved in reducing feed digestion. An in vitro experiment was carried out to study the effect of ruminal pH (6.4, 6.1, 5.8 and 5.5) on the digestion of fresh alfalfa. RESULTS: Decreasing the pH, in vitro gas production (ivGP) decreased (P < 0.05). The lowest ivGP was registered at pH 5.5 and it was product of a higher lag time and a lower digestion rate. Dry matter disappearance (DMD) was not affected by pH at 48 h (P > 0.05). Neutral detergent disappearance (NDFD) at 48 h decreased below pH 6.1. The NDFD was reduced by 62% at pH 5.5 with respect to results at pH 6.4 and 6.1 (where the highest DMD and NDFD were observed). CONCLUSION: As expected, low rumen pH decreased alfalfa digestion. However, limits to ruminal digestion activity differed from those usually proposed for TMR diets. It is apparent that different relationships between rumen pH and NDFD exist when cows graze fresh alfalfa or grasses. Moreover, our results suggest the convenience to complement the data obtained through ivGP, DMD and NDFD. While ivGP and DMD seem to be more useful at early digestion times, NDFD may be a good predictor of final digestion.

Carcass and meat characterization of "yacare overo" (Caiman latirostris) and "yacare negro" (Caiman yacare) / Carcaça e qualidade da carne dez jacarés (Caiman latirostris ou jacaré-de-papo amarelo e Caiman jacaré)

Ten caimans (Caiman latirostris and Caiman yacare) of different length and live weight were slaughtered to assess carcass yield and meat quality traits. Carcass yield was 54% while meat portion was the 62%. The carcass meat/bone ratio was approximately 1,51 while the 6,4% corresponded to the fat depots, mostly visceral depots. The tail cut represented the 27,4% of the carcass weight and it was composed 21,9% by meat and the 5,5% of bone. The meat tail pH postsmortem value (6,88 ±0,22) fell up to 6,49 (±0,23), 24 hs after slaughtering and 5,85 (±0,12) after thawing. Cookinglosses were low (<0,3%) and the Warner Bratzler shear force had values lower than 3kg. The raw tail color analyses characterized the meat as luminous (L *= 67,7) and pale (C*= 5,5). While the fat content changed significantly depending on the tive weight (2,5-29,8%DM), the protein content was relatively constant and around the 65% of dry matter. From the total intramuscular fatty acid content of tail meat, the 41,4 % were satured, the 39,1 % were monounsatured and the 10,7% were polyunsatured, with a n-6/ n-3 ratio near the optimum (3,16 vs 4). The oleic acid was the most important FA foLlowed by the palmitic, stearic and Moleic acids. Among the unsatured FA, the levels of essential FA as araquidonic (4,34) and n-3 derived family were important (EPA= 0,76 and DHA= 0,57). Another positive nutritional characteristic was the high level of CLA (1,87%FAtot).

Dez jacarés (Caiman latirostris ou jacaré -de-papo amarelo e Caiman jacaré) de diferentes comprimentos e pesos vivos foram carneados com o fim de determinar valores de rendimento de carcaça e qualidade da carne. O rendimento de carcaça foi de 54% correspondendo um 62% a porção cárnea. A relação Carne/ Osso da carcaça se estimou em aproximadamente 1,51 enquanto que 6,4% correspondeu a depósitos gordurosos, fundamentalmente periviscerais. O rabo representou 27,4% do peso de carcaça estando composta por 21,9% de carne e 5,5% de osso. O valor de pH post mortem, 6,88 ± 0,22 medido no rabo, decresceu até 6,49 ± 0,23 às 24h e 5,85 ± 0,12 logo de descongelamento. As perdas de cocção se contiveram (<0,3%) e a dureza Warner Bratzler mostrou valores inferiores a 3 kg. A análise da cor da carne crua permite caracterizá-la como una carne luminosa (L*=67,7) e clara (C*= 5,5). Enquanto que o conteúdo gorduroso variou significativamente em função do peso (2,5-29,8%MS), a porcentagem protéica foi relativamente constante e próxima a 65%MS. Do total de ácidos gorduroso do rabo, 41,4% foram saturados, 39,1 % monoinsaturados e 10,7% poliinsaturados, com uma relação n-6/n-¬3 próxima a ótimo (3,16). O ácido gorduroso foi o predominante seguido pelos ácidos palmitico, esteárico y linoléico. Dentro dos insaturados, foi elevado o conteúdo de ácidos gordurosos essenciáis= araquidônico (4,34) e família n-3 (EPA=0,76 e DHA=0,57); a esta característica nutritiva positiva se soma o alto conteúdo em CLA (1 , 87%Agtot).

Evaluation of two procedures to determine acid and neutral detergent fibers in ruminant feeds of the temperate region of Argentina.

The objective of this work was to compare the traditional Van Soest's procedure to analyze neutral detergent fibers (NDF) and acid detergent fibers (ADF) using filtering crucibles (VS) with a semiautomatic method which uses filter bags in an ANKOM Technology Corp. instrument (ANK). Nine ruminant feeds widely used in the temperate region of Argentina were analyzed: soybean meal expeller, alfalfa, pasture silage, ryegrass, corn silage, weeping lovegrass, tall wheatgrass, guinea grass, and barley grass. Four runs were done for each technique and feed. The comparison of ADF and NDF means by the means test for paired samples showed no significant differences between techniques (alpha = 0.01). The variability among runs was greater with the VS method than the ANK, both for NDF, standard deviation (SD) = 0.71 vs 0.39, and for ADF, SD = 0.83 vs 0.56, but the differences were not significant. The linear regressions were VS = 1.43 + 0.95 ANK; R2 = 0.99, and VS = 0.53 + 0.98 ANK; R2 = 0.99 for NDF and ADF, respectively, which indicated a strong linear relationship among the results of both procedures. It was concluded that the ANK procedure gave results comparable to those of the VS method when ruminant feeds from the temperate region of Argentina were analyzed.