Effect of duration and pattern of underfeeding in early lactation on milk production and reproduction of dairy cows

Abstract

Eighty cows of mixed breeds were fed so that they calved in moderate condition, and were then strip-grazed at different rates over the first ten weeks of lactation. Two levels of feeding were used factorially ; either ad libitum pasture intake (H) or an allowance of pasture which resulted in an intake of 7 kg of pasture dry matter cow-1 day-1 (L), for the first or second five-week period. After ten weeks, all cows were grazed as one group as well as seasonal conditions permitted. The effects of five-week periods of underfeeding on milk, milk fat and protein yield were equal and additive over the first ten weeks of lactation, HL and LH groups producing 11 kg and LL group 22 kg less milk fat than the HH group. Residual effects, however, from week 11 to the end of lactation differed markedly between treatments, the LH group producing the same as, but HL and LL groups producing 9 and 21 kg less than, the HH group. Residual effects of only 0.7 and 1.0 times the immediate effect were recorded for underfeeding in the first five and ten weeks of lactation, respectively. Cows underfed in early lactation gained more liveweight in later lactation at the expense of milk yield. An extra 10 kg pasture dry matter was required in early lactation to give an extra kilogram of milk fat over the lactation. The calving to conception interval in the LL group was 18 days longer than in the HH group (P < 0.05). The delay was associated with both a longer post-partum anoestrus and a higher number of services per conception. There was no effect of stage of underfeeding (HL vs LH) on reproductive performance. The poor understanding of factors affecting residual effects from underfeeding in early lactation is highlighted. As pattern of underfeeding has little effect on lactation performance, this gives the farmer considerable flexibility in allocating feed supplies in early lactation.

Effect of the levels of N fertilizer, grass and supplementary feeds on nitrogen composition and renneting properties of milk from cows at pasture

“…The response in milk protein content to an increased grass availability and thereby to an increased energy intake is in line with general theory and observations (Journet & Remond, 1980;DePeters & Cant, 1992) and other grazing experiments (Grainger & Wilhelms, 1979). The unchanged distribution of N between the different fractions of milk proteins probably indicates that the increased availability of clover grass has efficiently supplied the cow with more energy and more amino acids at the duodenum, and this was also reflected in a higher milk yield (~ 10%).…”

Energy transfer and female condition in nursing harp seals Phoca groenlandica

“…Fisher (1954) reported girth and length data for female seals sampled in January of 1950-1952 in the Gulf of St. Lawrence. Generally his seals were shorter than average females collected in 1976 and 1978, but not shorter than those sampled in 1979(Tab. I).…”

“…Since females feed in southern waters after weaning their pups (Sergeant 1973). one possible hypothesis is that this management change resulted in a sudden increase in competition for food between pups and females after weaning, suppressing pup growth and resulting in the smaller adults of the 1979samples (Inncs et al 1981. As the change in legislation included harp seals whelping off Newfoundland as well, no special fidelity to breeding site need be evoked to limit this discussion to the Gulf.…”

Reproduction Performance and Management of Dairy Cattle

“…Body condition score (BCS), a proxy for energy balance, has been shown to be associated with a number of reproductive outcomes. Low BCS at calving is associated with extended post partum anoestrous intervals [25], lower submission rates [7], lower first service conception rates [5,7] and lower 6-week pregnancy rates [5]. Conception rates decline with excessive losses of BCS post partum both in pasture based systems [5] and more intensive management systems [17,26,27].…”