ABSTRACT
On-farm methane (CH4) emissions need to be estimated accurately so that the mitigation effect of recommended practices can be accounted for. In the present study prediction equations for enteric CH4 have been developed in lieu of expensive animal measurement approaches. Our objectives were to: (1) compile a dataset from individual beef cattle data for the Latin America and Caribbean (LAC) region; (2) determine main predictors of CH4 emission variables; (3) develop and cross-validate prediction models according to dietary forage content (DFC); and (4) compare the predictive ability of these newly-developed models with extant equations reported in literature, including those currently used for CH4 inventories in LAC countries. After outlier's screening, 1100 beef cattle observations from 55 studies were kept in the final dataset (â¼ 50 % of the original dataset). Mixed-effects models were fitted with a random effect of study. The whole dataset was split according to DFC into a subset for all-forage (DFC = 100 %), high-forage (94 % ≥ DFC ≥ 54 %), and low-forage (50 % ≥ DFC) diets. Feed intake and average daily gain (ADG) were the main predictors of CH4 emission (g d-1), whereas this was feeding level [dry matter intake (DMI) as % of body weight] for CH4 yield (g kg-1 DMI). The newly-developed models were more accurate than IPCC Tier 2 equations for all subsets. Simple and multiple regression models including ADG were accurate and a feasible option to predict CH4 emission when data on feed intake are not available. Methane yield was not well predicted by any extant equation in contrast to the newly-developed models. The present study delivered new models that may be alternatives for the IPCC Tier 2 equations to improve CH4 prediction for beef cattle in inventories of LAC countries based either on more or less readily available data.
Subject(s)
Animal Feed , Methane , Animals , Cattle , Animal Feed/analysis , Latin America , Diet/veterinary , EatingABSTRACT
Abstract Background: The nutritional limitations of Cenchrus clandestinus -i.e., high protein and low energy concentrations- make it necessary to supplement cows with non-fibrous carbohydrate (NFC) sources to improve productive performance. Nevertheless, such supplementation can lead to ruminal acidosis. Objective: To evaluate partial replacement of corn grain (Zea mays, ZM) with sorghum grain (Sorghum vulgare, SV), cassava root (Manihot esculenta, MES) or citrus pulp (Citrus sp., C) on milk yield and quality, ruminal pH and health of grazing cows. Methods: Eight Holstein cows were evaluated in a 4 x 4 Latin square design during the first 60 days of lactation. Treatments (isoenergetic rations, 1.45 ± 0.003 Mcal NEL/kg DM) consisted of a mixture of grass and four concentrates with different NFC sources. Results: No differences in dry matter intake, feed efficiency, ruminal pH, hematological and metabolic profile were observed between treatments. Rumen pH was higher than 6.0, confirming the absence of ruminal acidosis. Milk yield (energy-corrected), protein, and total solids were higher for MES vs. C. Conclusions: None of the NFC sources tested compromised the ruminal or systemic health of the cows, while MES improved milk yield and quality.
Resumen Antecedentes: las limitaciones nutricionales del Cenchrus clandestinus (alta concentración de proteína y baja densidad energética) hacen necesario suplementar las vacas con fuentes de carbohidratos no fibrosos (NFC) para mejorar su desempeño productivo. Sin embargo, esta suplementación puede generar acidosis ruminal. Objetivo: evaluar el reemplazo parcial de maíz (Zea mays, ZM) por sorgo (Sorghum vulgare, SV), yuca (Manihot esculenta, MES) o pulpa cítrica (Citrus sp., C) sobre la producción de leche y su calidad, el pH ruminal y la salud de vacas en pastoreo. Métodos: ocho vacas Holstein fueron evaluadas empleando un diseño en cuadrado latino de 4 x 4 durante los primeros 60 días de lactancia. Los tratamientos (raciones isoenergéticas, 1,45 ± 0,003 Mcal NEL/kg MS) consistieron de una mezcla de forraje y cuatro concentrados con diferentes fuentes de NFC. Resultados: no se observaron diferencias entre tratamientos en cuanto a consumo de materia seca, eficiencia alimenticia, pH ruminal, ni perfiles hematológico y metabólico. El pH ruminal fue mayor a 6,0; confirmando la ausencia de acidosis. La producción de leche (corregida por energía), proteína, y sólidos totales fue mayor para MES vs. C. Conclusiones: ninguna de las fuentes de NFC evaluadas comprometieron la salud ruminal o sistémica de las vacas, y MES mejoró la producción de leche y su calidad.
Resumo Antecedentes: as limitações nutricionais do Cenchrus clandestinus-alta concentração de proteína e baixa densidade de energia- faz necessário suplementar às vacas com fontes de carboidratos não-fibrosos (NFC) para melhorar o desempenho produtivo. No entanto, essa suplementação pode gerar acidose ruminal. Objetivo: avaliar a substituição parcial do milho (Zea mays, ZM) por sorgo (Sorghum vulgare, SV), mandioca (Manihot esculenta, MES) ou polpa cítrica (Citrus sp., C) na produção e qualidade do leite, pH ruminal e a saúde de vacas em pastejo. Métodos: oito vacas Holandesas foram avaliadas empregando um delineamento em quadrado latino 4 x 4 durante os primeiros 60 dias de lactação. Os tratamentos (rações isoenergéticas, 1,45 ± 0,003 Mcal NEL/kg DM) consistiram de uma mistura de forragem e quatro concentrados com diferentes fontes de NFC. Resultados: não foram observadas diferenças entre os tratamentos no consumo de matéria seca, eficiência alimentar, pH ruminal, perfil hematológico e metabólico. O pH ruminal foi superior a 6,0; confirmando a ausência de acidose ruminal. A produção do leite (corrigida para energia), proteína e sólidos totais foi maior para MES vs. C. Conclusões: nenhuma das fontes de NFC avaliadas comprometeu a saúde ruminal e sistêmica das vacas, embora o MES melhorou a produção e qualidade do leite.
ABSTRACT
The apparent total tract digestibility (ATTD) of nutrients can be assessed by total collection of faeces (TC), which is the reference method, or by the indicator method (IM). Little information is available on proper faecal sampling methodologies for IM in canines to obtain results comparable to TC. The objective of this study was to determine the minimum number of sub-samples required for the IM to make it comparable with TC. A total of 11 adult male dogs were individually housed in metabolism cages. Dogs had access to a grass yard to facilitate defaecation. Faecal sub-samples (1/day) were taken from the daily faecal output to prepare the pooled samples for IM, obtaining cumulative sample combinations of 3 (IM3), 4 (IM4), 5 (IM5), 6 (IM6) and 7 d (IM7). Digestibility of dry matter, gross energy, crude protein and crude fibre was similar between TC and IM5, IM6 and IM7 (p > 0.05). The IM7 presented the greatest statistical similarity with TC. Nevertheless, IM was not a good predictor of crude fibre digestibility. In conclusion, IM can replace the TC method in dogs to evaluate ATTD of several nutritional fractions as long as the composite sample is collected during seven consecutive days. For estimation of fibre digestibility by IM, longer collection periods are probably required.
Subject(s)
Animal Nutrition Sciences/methods , Digestion , Nutrients/metabolism , Physiology/methods , Animal Nutritional Physiological Phenomena , Animals , Diet/veterinary , Dogs , Feces , MaleABSTRACT
La técnica de degradación in situ ha sido ampliamente adoptada para evaluar la tasa y la extensiónde la degradación de los alimentos en el rumen. Los nuevos modelos para formulación y evaluación deraciones requieren de la determinación precisa de aspectos dinámicos de la degradación de alimentosen el rumen y han adoptado a la técnica in situ como instrumento para facilitar este tipo de mediciones.Numerosas son las fuentes de variación relacionadas con la técnica que pueden alterar las estimativasde la tasa y la extensión de la degradación, entre ellas podemos citar: el tamaño de los sacos de nylon, eltamaño de los poros del saco, la posición de los sacos dentro del rumen, el tamaño de partícula del alimentoy el procesamiento matemático de la información. Diferentes modelos matemáticos han sido propuestospara estudiar la cinética de degradación. En la construcción de estos modelos han sido tenidas en cuentalas características particulares del sustrato en estudio, aspectos anatómicos y fisiológicos del animal yprocesos relacionados con la hidratación y colonización del sustrato por parte de los microorganismosruminales. El objetivo de este trabajo fue discutir algunos modelos utilizados en el estudio de la cinética dedegradación del alimento mediante su descripción matemática y aplicación práctica.
The in situ degradation technique has been adopted to evaluate the rate and extent of ruminal fooddegradation. The new models for formulation and evaluation of foods require of the precise determinationof the dynamic aspects of ruminal foods degradation for which the in situ technique has been adopted inorder to facilitate its mathematical determination. Different sources of variation related with the techniqueitself can alter the rate and extent of food degradation: the size of nylon bag, pore size, specific placement ofthe bag into the rumen, particle size of food and the mathematical models used for analyses, among others.Different models have been proposed for degradation kinetic studies. In these models the characteristicsof food samples, anatomical and physiologic aspects of the animal, as well as those processes related withthe hydrate and colonization of samples by ruminal microorganism have been considered. The objective ofthis work was to discuss some of the models used to evaluate the rate and extent of food degradation in therumen by the mathematical description and practical application of the in situ technique.
