In vitro gas and methane production in rumen fluid from dairy cows fed grass silages differing in plant maturity, compared to in vivo data.

The relationship between in vitro rumen CH4 production of grass silages, using the gas production technique, and in vivo data obtained with the same cows and rations in respiration chambers was investigated. Silages were made from grass harvested in 2013 on May 6th, May 25th, July 1st and July 8th. The grass silages were used to formulate four different rations which were fed to 24 cows in early and late lactation, resulting in a slightly different dry matter intake (DMI; 16.5 kg/day vs. 15.4 kg/day). The experimental rations consisted of 70% grass silage, 10% maize silage, and 20% concentrates on a dry matter basis. Cows were adapted to the rations for 17 days before rumen fluid was collected via oesophageal tubing, and in vitro gas and CH4 production were analysed. In vitro total gas and CH4 production of the (ensiled) grass expressed as ml/g OM decreased with advancing maturity of the grass. The in vitro CH4 production after 48 hr of incubation expressed in ml/g OM did not correlate with the in vivo CH4 production expressed in g/kg organic matter intake or g/kg DMI (R2  = .00-.18, p ≥ .287). The differences in CH4 emission per unit of intake observed in vivo were rather small between the different rations, which also contributed to the observed poor relationship. Utilizing stepwise multiple regression improved the correlation only slightly. In vitro gas and CH4 production varied based on whether donor cows were previously adapted to the respective ration or not, suggesting that careful adaption to the experimental diet should be envisaged in in vitro gas and CH4 production experiments.

In vitro gas and methane production of silages from whole-plant corn harvested at 4 different stages of maturity and a comparison with in vivo methane production.

The current study investigated the relationship between in vitro and in vivo CH4 production by cows fed corn silage (CS)-based rations. In vivo CH4 production was measured in climate respiration chambers using 8 rumen-cannulated Holstein-Friesian cows. In vitro CH4 production was measured using rumen fluid from the 8 cows that were fully adapted to their respective experimental rations. The animals were grouped in 2 blocks, and randomly assigned to 1 of the 4 total mixed rations (TMR) that consisted of 75% experimental CS, 20% concentrate, and 5% wheat straw [dry matter (DM) basis]. The experimental CS were prepared from whole-plant corn that was harvested at either a very early (25% DM), early (28% DM), medium (32% DM), or late (40% DM) stage of maturity. The 4 experimental TMR and the corresponding CS served as substrate in 2 separate in vitro runs (each run representing 1 block of 4 animals) using rumen fluid from cows fed the TMR in question. No relationship was found between in vivo CH4 production and in vitro CH4 production measured at various time points between 2 and 48 h. None of the in vitro gas production (GP) and CH4 production parameters was influenced by an interaction between substrate and origin of rumen fluid. In vitro measured 48-h GP was not affected by the maturity of whole-plant corn, irrespective whether CS alone or as part of TMR was incubated in adapted rumen inoculum. Incubation of the experimental TMR did not affect the kinetics parameters associated with gas or CH4 production, but when CS alone was incubated the asymptote of GP of the soluble fraction was slightly decreased with increasing maturity of CS at harvest. In vitro CH4 production expressed as a percent of total gas was not affected by the maturity of whole-plant corn at harvest. Several in vitro parameters were significantly affected (GP) or tended to be affected (CH4) by diet fed to donor cows. It was concluded that the current in vitro technique is not suitable to predict in vivo CH4 production from CS-based rations.

Componentes corporais de caprinos jovens ¾ Boer submetidos a dietas com óleo de licuri (Syagrus coronata) / Body components of young crossbred Boer goats fed licury oil (Syagrus coronata) in the diet

Determinou-se o melhor teor de óleo de licuri na dieta por intermédio das características dos componentes corporais de caprinos jovens ¾ Boer. Foram utilizados 19 caprinos inteiros, com média de idade inicial de três meses e média de peso de 10,8kg. Os animais foram alimentados com feno de Tifton-85 e mistura concentrada com 0; 1,5; 3,0 e 4,5 por cento de óleo de licuri. O experimento durou 60 dias; no último dia, os animais foram abatidos para avaliação das características dos componentes do peso corporal. O peso corporal ao abate, o peso de carcaça fria, o rendimento comercial, o rendimento de frigorificação, a área de olho de lombo, a proporção músculo:osso, os índices de compacidade de medidas biométricas, o peso dos cortes comerciais e o rendimento das vísceras comestíveis não carcaça não foram influenciados pela adição do óleo de licuri à dieta. O peso das vísceras comestíveis não carcaça e o índice de musculosidade do pernil sofreram influência negativa da adição do óleo na dieta. O óleo de licuri pode ser adicionado na dieta de caprinos jovens ¾ Boer até 4,5 por cento, sem causar alterações significativas na carcaça.

The best level of licury oil in the diet was evaluated by meat compounds of male young ¾ Boer goats. Nineteen goats were used, with initial weight of 10.8kg/LW. The animals were fed Tifton-85 hay and concentrated mix with 0.0, 1.5, 3.0, and 4.5 percent of licury oil. The experiment lasted 60 days and, on the last day, the animals were submitted to feed fasting and slaughtered, in order to evaluate the characteristics of the live weight components. The body weight at slaughter, carcass weight, commercial yield, freezing yield, loin eye area, muscle-bone ratio, compactness carcass index, biometric measurements, commercial cuts weights, and edible viscera yield were not influenced by the licury oil added to the diet. The edible viscera weight and ham muscularity index were negatively influenced by the oil. Then, it could be added to diet of young ¾ Boer goats up to 4.5 percent without causing significant changes in the carcass.