Seasonal strategic feed supplements for sheep grazing Caatinga rangeland: Behavior and performance

Abstract

The objective of this study was to evaluate the impact of concentrate feed supplements associated to seasonal conditions on performance and behavior of ewe grazing Caatinga rangeland from late gestation to lamb weaning. Treatments included supplements at 0, 200, 350 and 500 g concentrate/head/day during the rainy, transition or dry season for 3 years. Supplement during the rainy season stimulated dry matter intake (DMI), digestible protein (DCPI) and total digestible nutrients (TDNI). Feed supplement during the rainy season, when ewes were in their last third of gestation, resulted in greater nutrient offered than required for their elevated nutritional demands, allowing them to utilize forage of better nutritive value when grazing Caatinga rangeland. Greater reproductive efficiency and birth rates resulted. Supplementing feed at 350 g/day or more increased dietary total digestible nutrients (TDN) and crude protein (CP), contributing to greater ewe performance, favoring body weight and condition score maintenance from lambing to lamb weaning while supplementing at 500 g/day during the rainy season increased twinning rates. During the dry season, feed supplement partially substituted rangeland forage but increased overall ewe diet DMI and nutrient digestibility due to greater diet TDN and CP during lamb weaning. Global positioning system data indicated a seasonal impact on ewe behavior and energy use during foraging and seeking out water on semiarid tropical rangeland, notably greater energy expenditure moving during the dry season while ingesting 26.1 % less forage DM that did not meet reproductive requirements. Supplements met this deficit and increased ewe reproductive efficiency.