The objective of the present study was to estimate genetic parameters for test-day milk, fat and protein yields and 305-day-yields in Murrah buffaloes. 4,757 complete lactations of Murrah buffaloes were analyzed. Co-variance components were estimated by the restricted maximum likelihood method. The models included additive direct genetic and permanent environmental effects as random effects, and the fixed effects of contemporary group, milking number and age of the cow at calving as linear and quadratic covariables. Contemporary groups were defined by herd-year-month of test for test-day yields and by herd-year-season of calving for 305-day yields. The heritability estimates obtained by two-trait analysis ranged from 0.15 to 0.24 for milk, 0.16 to 0.23 for protein and 0.13 to 0.22 for fat, yields. Genetic and phenotypic correlations were all positive. The observed population additive genetic variation indicated that selection might be an effective tool in changing population means in milk, fat and protein yields.

Considerando que el recuento de células somáticas (RCS) de muestras de leche es una valioso indicador de la salud de la ubre de búfalas, se desarrolló el presente trabajo con el fin de estimar la relación existente entre algunos factores ambientales y el RCS, verificando la frecuencia de ocurrencia de muestras analizadas en clases de recuentos muy altos, altos, medios y bajos. Fueron analizadas informaciones de 23.534 muestras de controles de leche (RCS), referentes a 2.198 lactancias de animales de la raza murrah con edades entre los dos y quince años, hijas de 187 reproductores; estos muestreos fueron realizados durante siete años. Los resultados indicaron que de manera general, ocurrieron bajos, medios, altos y muy altos RCS para, 96,34%, 2,3%, 0,96% y 0,4% de las muestras, respectivamente. Las clases de bajos y medios RCS, fueron las que presentaron las mayores frecuencias, confirmando que en búfalos, hay una tendencia a menores recuentos que en los bovinos. Se presentaron diferencias entre las medias del RCS por orden de parto y por estación de parto, y hubo diferencias estadísticamente significativas (P < 0,05) para las medias del RCS en algunos controles. En relación con el orden de parto fueron observadas diferencias entre las frecuencias de los RCS, siendo que, de modo general, a medida que aumentó el orden del parto, disminuyó el porcentaje de bajos recuentos y aumentaron las frecuencias de recuentos medios, altos y muy altos. Los resultados indicaron que los efectos de hacienda, año y orden de parto deben ser considerados en la comparación entre animales.

This study was performed in order to estimate the relation between some environmental factors and somatic cell count (SCC). This relation was verified by testing the frequency of analyzed samples in classes according to the SCC as follows: very high, high, medium and low. 23,534 milk samples corresponding to 2.198 lactations of Murrah breed animals were used. The buffaloes were between 2 and 15 years old and were daughters of 187 males. The samples were taken during a period of 7 years. In general, the results showed that SCC was low, medium, high and very high for 96.34%, 2.3%, 0.96% and 0.4% for the samples, respectively. Low and medium SCC had the highest frequencies, pointing out that in buffaloes there is a tendency of lower SCC when compared to bovines. There were differences between the average SCC according to the order and season of parturition. There were also significant differences between the average SCC of some control samples (P<0.05). In relation to order of parturition there were observed differences between SCC frequencies, but as a general statement it was observed that as order of parturition was higher the rate of lower SCC decreased and the frequency of medium, high and very high SCC increased. The results indicated that the effects of farm, year and order of parturition should be considered when comparing animals