Maintenance energy requirement and efficiency of utilisation of metabolisable energy for milk production of Bos taurus × Bos indicus crossbred tropical dairy cows: a meta-analysis

Abstract

ContextDairy consumption has the ability to provide nutrient dense food in low-income countries. However, cows in the tropics may not be able to reach their full potential due to poor nutrition. In tropical regions, milk is mostly produced by Bos taurus × Bos indicus crossbred cattle for which no nutrient requirement tables have been fully developed. Although many novel feeds and feed additives have been tested, nutrient requirements specifically targeting energy and protein for these livestock need to be estimated accurately for milk production to increase sustainably. AimsTo determine the net energy for lactation (NEL) requirement for maintenance and efficiency of utilisation of metabolisable energy intake (MEI) for milk production (kL) of Bos taurus × Bos indicus crossbred dairy cows in the tropics. MethodsA meta-analysis using 141 observations from 38 independent studies in tropical regions with crossbred dairy cows was conducted. The energy produced in milk corrected for zero energy balance (EL0) was regressed by MEI including other covariates. This meta-regression analysis was conducted by frequentist inference via optimisation in RStan. Key resultsThe best-fit model contained only MEI as a covariate. This model predicted a net energy for lactation value at maintenance of 0.323 MJ/kg BW0.75.day (s.e. = 0.0004) with variations for each specific study. The efficiency with which MEI is used for milk production was estimated to be 0.554 (s.e. = 0.00008), which was common for all studies. ConclusionThe key energy parameters estimated in this study should replace commonly used values derived from Bos taurus breeds when formulating diets for crossbred tropical cattle. ImplicationsNutritional requirement tables need to be estimated specifically for Bos taurus × Bos indicus crossbred dairy cows as their requirements differ from Western breeds. Using appropriate nutritional requirements of crossbred cattle would lead to better nutrition and increased production as determined by their genetic merit.