Cuatro aspectos generales deben considerarse:a) momento de muestreo, b) profundidad de muestreo, c) número de tomas y d) manejo de las muestras.

Abstract: The objective of this study was determine whether the amount of protein provided to cows during late gestation would affect postnatal growth and lead to changes on glucose, insulin and insulin-like growth factor concentrations. At 134 d prepartum, 68 multiparous Angus cows were blocked by BW and expected calving date and randomly assigned to low protein level (LP, 6% CP) or high protein level (HP, 12% CP) and were allotted in 12 pens per treatment. At calving, cows were managed together on improved pastures until weaning.

Abstract: The effect of level of CP fed during late gestation on reproductive performance and milk production was studied in multiparous cows. Sixty-eight pregnant Angus cows were used. At 121 d prepartum, cows were blocked by BW (409 ± 57 kg) and expected calving date, randomly assigned to a low-protein (LP = 6% CP) or high-protein diet (HP = 12% CP), and allocated to 12 pens per treatment. After parturition, all cows were managed in a single group until weaning.

Abstract: The effect of level of CP fed during late gestation on reproductive performance and milk production was studied in multiparous cows. Sixty-eight pregnant Angus cows were used. At 121 d prepartum, cows were blocked by BW (409 ± 57 kg) and expected calving date, randomly assigned to a low-protein (LP = 6% CP) or high-protein diet (HP = 12% CP), and allocated to 12 pens per treatment. After parturition, all cows were managed in a single group until weaning.