SUMMARY
Other than crude protein (CP), crude energy (CE) and crude fiber (CF) content, the adequate supply of essential amino acids (EAA) is an important factor in milk replacer evaluation. The aim of this study was to analyze milk replacer samples as regard to nutrients, especially EAA, composition and simulate the attainability of calves' requirements in different feeding systems. Forty-one milk replacer samples were collected from 14 brands and analyzed for nutrient composition. The near infrared spectroscopy technique was used for AA content estimation. Samples presented adequate levels of CP (21.2±2.90%) and ether extract (14.5±3.41%) for calves fed according to the conventional (4L/d), but not for intensive milk feeding system (>6L/d). High values of CF were observed in the samples (1.6±0.86%). The EAA composition of milk replacer samples was lower than expected for a liquid feed supposed to replace whole milk. None of the analyzed samples presented adequate lysine (5.72±1.09% CP) or methionine (1.65±0.38% CP) to meet calves' daily requirements, regardless of feeding system. Higher crude protein milk replacers are needed. Alternatively, supplementation of milk replacers with EAA is recommended.
Keywords:
calves; lysine; methionine; weaning