Abstract
The objective of this work was to assess the effects of including fibrous concentrates to pTMR diets for lambs. In a Rusitec system of 6 fermentation units (900 mL), 4 diets were evaluated: 100% alfalfa (ALF), 100% TMR, 30% alfalfa and 70% fibrous TMR (pTMRf) and 30% alfalfa and 70% starchy TMR (pTMRs)(Table 1). A balanced incomplete block design was used; 4 runs were made with 3 diets in duplicate incubated at a time, thus each diet had 3 independent measures. Runs lasted 10d, first 5d for system equilibration and last 5d for sampling. Ten grams of DM of each diet were incubated in nylon bags and changed every 48h. The inoculum was obtained from 2 rumen fistulated cows fed with alfalfa hay ad libitum, 2.5 kg/d of ground corn and 2.5 kg/d of corn germ meal. McDougalĹs artificial saliva was infused at a 3%/h rate. Samples were taken every day from the fermentation unit at the same time bags were changed. Measurements of pH, DM disappearance, N-NH3 and VFA concentrations were made. Data were analyzed according to a repeated measures model and preplanned orthogonal contrast were performed. Alfalfa diet showed the highest pH (p3 concentration was higher for ALF diet, followed by pTMRs, pTMRf and lowest for TMR. DM disappearance was higher for diets that included alfalfa (ALF, pTMRf and pTMRs). These results indicate advantages of pTMR diets, and that including a fibrous concentrate in pTMR diets could enhance microbial protein synthesis and butiric acid production.
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