Gladis Ferreira Correa

Produção e composição química do leite em diferentes genótipos ovinos

The objective of this study was to evaluate production and chemical components of milk from Corriedale sheep and Corriedale x Milchschaf breed. Thirty-three Corriedale, 43 Corriedale x Milchschaf (F1), and 23 F1 (Corriedale x Milchschaf) x Milchschaf (F2) were used. Animals were milked twice daily, from September to December 2002. A total of five milking evaluation periods with a 21-day interval was conducted. Fat, protein and lactose contents were determined. A completely randomized design was used to evaluate the effect of genotype in milk production, corrected for 100 days and yield of fat, protein and lactose. In the mathematical model, age, number of sheep born and body condition were used as co-factors. Significant difference (P<0.0001) was found between genotypes in terms of milk production (kg), fat, protein, and lactose (g) corrected for 100 days of lactation. Genotypes F1 and F2 were the most productive.

PRODUÇÃO E COMPOSIÇÃO QUÍMICA DO LEITE DE OVELHAS CORRIEDALE E CRUZAS MILCHSCHAF

O trabalho foi desenvolvido no Campo Experimental no 1, da Faculdade de Veterinaria de Montevideu (Uruguai), com o objetivo de comparar a producao e composicao do leite de diferentes genotipos ovinos. Foram utilizadas 33 ovelhas da raca Corriedale , 43 cruzas F1 ( Corriedale x Milchschaf ) e 23 cruzas F2 (F1 x Milchschaf ), ordenhadas de setembro a dezembro de 2002, a partir da sexta semana de lactacao, totalizando cinco controles leiteiros, com intervalo de vinte e um dias. As amostras de leite foram analisadas na Cooperativa de Laboratorios Veterinarios de Colonia (COLAVECO) para determinacao dos teores de gordura, proteina e lactose. Os animais foram alimentados com pastagem cultivada consorciada de azevem ( Lolium multiflorum Lam ), trevo branco ( Trifolium repens Lam ) e cornichao ( Lotus corniculatus Lam ), com disponibilidade media de 2,1 tMS ha -1. Foi utilizado o delineamento completamente casualizado com parcelas subdividas. Houve interacao entre genotipo e semanas de lactacao. Foi observada diferenca significativa entre genotipos para producao de leite (L/dia) e teores de gordura e lactose na decima segunda semana, nao havendo diferenca no teor de proteina. Na sexta semana de lactacao nao houve diferenca entre genotipos para os parâmetros avaliados. Houve diferenca significativa entre as semanas de lactacao, na avaliacao separada de cada genotipo. A raca Corriedale e uma alternativa para cruzamento com racas leiteiras, quando a finalidade e associar incremento de producao com adaptabilidade. Palavras chave: Componentes do leite ovino, lactacao, ovinos leiteiros ABSTRACT This study was carried out at Campo Experimental no 1 (Veterinary Medicine School – Montevideo, ROU), to evaluate the production and chemical composition of milk from different sheep genotypes. Thirty three (33) Corriedale breed sheep, 43 F1 ( Corriedale x Milchschaf ) crosses and 23 F2 (F1 x Milchschaf ), were milked from September to December 2002, from the 6th lactation onwards, totalizing five milking controls, with 21-days intervals. Milk samples were analysed at Cooperativa de Laboratorios Veterinarios de Colonia (COLAVECO) to determine contets of fat, protein and lactose. Animals were maintained in a raygrass x white clover x birdsfoot trefoil, pasture mixture, with a forage availability of 2.1 tDM ha-1. A split plot complete randomized desing was used. Interaction occurred between genotypes and lactation weeks. Significant difference was observed among genotypes for milk prodution (L/ dia ) and contents of fat and lactose in the 12th week and no difference for protein. In the 6th lactation week there was no difference among genotypes for all parameters. There was significant difference among lactation weeks when each genotype was evaluated separately. Corriedale breed constitutes a crossing alternative with specialized milk breeds, in order to associate increment in production with adaptability . Key words: Lactation, sheep milk components, sheep milking aptitude