Abstract
Productive and reproductive performance of beef heifers grazing on Italian ryegrass (Lolium multiflorum Lam.) were analyzed, comprising animals exclusively on pasture and supplemented animals with extruded fat (0.15 or 0.30% of body weight). The grazing method was continuous with variable stocking rate. The experimental design was completely randomized following a repeated measure arrangement. Variables related to pasture were similar when the heifers received different supplementation levels, with similar grazing conditions. Mean values of forage mass and canopy height were 1,500 kg DM ha-1 and 17 cm, respectively. Heifers ingested forage with a similar content of crude protein (21.90%) and neutral detergent fiber (49.30%), regardless of supplementation levels. Beef heifers supplemented with extruded fat, regardless of the level, had higher average daily gain, body weight, body condition score, body weight: height ratio than heifers fed exclusively on pasture. The use of extruded fat as a supplement caused no change in pelvic area and reproductive tract score in beef heifers. Regardless of their nutritional status, 14/15-month-old heifers were not able to conceive during the mating season.
Highlights
The use of Italian ryegrass (Lolium multiflorum Lam.) pasture by beef heifers is a strategy so that more animals reach faster the appropriate size for the onset of the reproductive activity
The above management provided the pastures with similar values of leaf:stem ratio (LSR)
Climatic data recorded in this study (Table 1) showed that monthly averages of rainfall, air temperature and insolation were close to the historical average, characterizing the evaluation period as normal
Summary
The use of Italian ryegrass (Lolium multiflorum Lam.) pasture by beef heifers is a strategy so that more animals reach faster the appropriate size for the onset of the reproductive activity. There are approximately 1.6 million heifers under one year in the state of Rio Grande do Sul, Brazil (Anuário da Pecuária Brasileira [Anualpec], 2014) and they are managed during fall and winter mainly on natural pastures. Animal Sciences the successful reproductive performance of beef heifers. International studies on the inclusion of fats in beef cattle diet have doubled in the last decade (Hess, Moss, & Rule, 2008; Guerrero et al, 2015), in Brazil, investigations on the subject are still fledging, mostly limited to milk production systems. The importance of producing results on fat inclusion in the diet of grazing beef cattle lies in the fact that lipids have a high concentration of readily
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