Performance of Bos indicus beef cattle supplemented with mineral or with concentrates in tropical Urochloa decumbens pastures: A meta-regression approach

Detoxified castor seed meal replaces soybean meal in the supplement for Holstein-Zebu crossbred steers finished on tropical pasture during the rainy season

The objective of this study was to examine the effect of replacing soybean meal (SBM) with detoxified castor seed meal (DCM) on the intake, digestibility, feeding behavior, and performance of pasture-finished (rainy season) steers supplemented with concentrate at 0.4% of their body weight. Forty ½ Holstein + ½ Zebu steers (initial weight: 283.3 ± 36.3 kg) were allocated to four treatments in a completely randomized experimental design. Treatments consisted of diets in which DCM replaced 0, 30, 60, and 90% of SBM in the supplement dry matter (DM). The steers were finished on an Urochloa brizantha pasture and the experiment lasted 112 days. Replacing SBM with DCM did not influence (P > 0.05) the intake or apparent digestibility of DM, crude protein, or neutral detergent insoluble fiber of the animals. Grazing time increased (P < 005), whereas the intake and rumination efficiencies of the steers did not change (P > 0.05) with the substitution. The replacement of SBM with DCM in the supplement fed to the steers also did not influence (P > 0.05) their final weight, average daily gain, or feed conversion (P > 0.05). We recommend replacing up to 90% (DM basis) of SBM with DCM in the concentrate supplement of steers grazing on Urochloa brizantha pasture during rainy season while supplemented with concentrate at 0.4% of their body weight.

Pigeon Pea Intercropped with Tropical Pasture as a Mitigation Strategy for Enteric Methane Emissions of Nellore Steers

In this study, we evaluate the effects of intercropping pigeon pea (Cajanus cajan (L.) Millsp.) with tropical pastures for feeding Nellore cattle and compared animal performance and enteric CH₄ emissions with other pasture-based systems during the dry and rainy seasons of 2021. Thirty-six Nellore steers (with a body weight of 221 ± 7 kg and an age of 15-16 months) were randomly distributed in three treatments with three replicates (in paddocks of 1.5 hectares each): (1) a degraded pasture of Urochloa spp. (DEG); (2) a recovered and fertilized pasture of Urochloa spp. (REC); and (3) pigeon pea intercropped with Urochloa spp. (MIX). Enteric CH₄ emissions were estimated using the sulfur hexafluoride (SF₆) tracer gas technique, and dry matter intake (DMI) was determined using internal (iNDF) and external (TiO₂) markers. Forages were collected by hand plucking after observations of ingestive behavior, and feces was collected after voluntary defecation. The proportion of grass and legume intake was estimated by C stable isotopes, and the forage nutritional quality was determined, while animal performance was monitored monthly, and the stocking rate was adjusted by the "put and take" technique. The results indicated that intercropping pigeon pea with tropical grasses is an interesting strategy for sustainable livestock production based on pastures. The MIX treatment was able to meet the nutritional requirements of the animals, which presented higher performance. In addition, there was a reduction in CH₄ emissions up to 70% when expressed per average daily weight gain in comparison to the DEG treatment.