[Effect of clinical mastitis on milk production]
1991
Pedraza G, Carlos
Ten years accumulated production and sanitary records were used. Main objectives were: - using a mathematical model, evaluate losses on milk production as a consequence of clinical mastitis; - observe the effect of mastitis on lactation in cows and heifers and on their later productive life; - evaluate the effects of the periods in which mastitis appears in the lactation curve. Production from healthy and sick animals were compared, after adjustment of the Wood's gamma function, y(n)=an EXP(b) x e EXP(-cn), where y(n) is the milk production on the (n) lactancy day and a, b and c are the estimated parameters for each curve, through a multiple lineal regression; establishing a total production, day and maximum production and decline index of the lactation curve. The research was accomplished with a total of 216 and 88 lactations, equivalent to an equal number of cows and heifers, half of which belong to healthy animals. Milk production (litres) obtained on the 300 days of healthy and sick cows were: 5,256a and 4,522b (P0.01), respectively. Considering the season on which mastitis appeared (summer, fall, winter, spring) production was: 5,005 and 4,861 N.S., 5,284a and 4,368b; 5,412a and 4,61 1b, and 5,085a and 4,079b (P
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