| Abstrakt: |
Simple Summary: Sheep producers in many countries of the world usually feed their animals with natural or improved pastures. In these situations, pastures alone usually do not cover animal needs, and supplementation is required. By-products from the oil industry are extensively used in animal feeding, and endosperm and mesocarp expellers from grugru palm may play an important role in animal feeding in the countries where it is distributed. To assess the protein value of an ingredient, the extent and rate of rumen degradation are central characteristics. However, associative effects with other components of the diet occur, and rumen degradation of individual ingredients should be assessed in the usual feeding conditions of an animal. On these grounds, the objective of this study was to provide information about rumen degradation of endosperm and mesocarp expellers from grugru palm in sheep grazing natural or cultivated monophytic pastures, and supplemented with a mixture of both expellers. The use of this mixture slows down the rate of degradation of the pastures, the effect of which is more intense in animals grazing natural swards. Supplementation with this mixture also increases the average daily gain of sheep, more substantially with multi-species natural pastures. Twenty-four ewes (eight fistulated in the rumen) were assigned to a 2 × 2 factorial design. The treatments included the pasture grazed (natural mixed swards—NMS or cultivated monophytic (Brachiaria brizantha cv. Marandu) swards—CMS) and the level of supplementation: without supplement or with a 1% supplement (dry matter (DM)/live weight). The supplement included one-third endosperm expeller (ENE) and two-thirds mesocarp expeller (ME) from Acrocomia aculeata (Jacq.) Lodd. ex Mart. In sacco rumen degradation of ENE, ME, NMS, and CMS was assessed in fistulated sheep, as were rumen fermentation variables. Average daily gain (ADG) was assessed in non-fistulated animals during a 7-week period. Potential degradability of the DM and crude protein of the expellers was not affected by the type of pasture grazed or the level of supplementation (p > 0.05), but the fractional rate of degradation (c) of DM was three times faster (p < 0.01) for ME than for ENE. The potential degradability of neutral detergent fiber was 34% higher (p < 0.0001) for ENE, with no differences in c (p > 0.1). Supplementation slowed down the c of the DM of the pastures, especially in animals grazing NMS (24% lower). Treatments affected rumen pH, concentration of volatile fatty acids, and proportion of valerate, in different ways. The use of the supplement increased ADG of sheep (six-fold in sheep grazing NMS and 40% in those grazing CMS). The use of a mixture of one-third ENE plus two-thirds ME as a protein supplement in sheep grazing either multi-species natural pastures or monophytic swards of Brachiaria brizantha cv. Marandu slows down the fractional rate of degradation of the pastures, the effect of which is more intense in animals grazing natural swards. This supplementation also increases average daily gain, more substantially with multi-species natural pastures. [ABSTRACT FROM AUTHOR] |
