| dc.description.abstract | Nine Friesian (405+21 kg) and nine Ayrshire (394+ 18 kg) lactating dairy cows were used to
determine the effects of reallocation of afixed amount of concentrate feed to different phases of
lactation on milk yield. They were blocked by breed and parity into six blocks and randomly
assigned within block to the three treatments in a randomised complete block design. The
treatments consisted of a commercial dairy meal concentrate supplementation supplied in two
daily meals distributed at milking of two kg/ day for 300 days (WL-2), four kg/day for 0-150 days
of lactation (HL-4) and eight kg/day for 0-75 days of lactation (QL-8). All the animals grazed
natural pasture (predominantly Kikuyu grass (penniseturn c1andestinum) and hadfree access to
un-chopped Rhodes grass (Chloris gayana) hay in the paddocks. The lactation yield (300 days) of
cows in QL-8, 3155.0 kg, was significantly (P<0.05) higher than for cows in WL-2 (2543.6 kg)
and HL-4 (2562.2 kg). Reallocation of concentrate (QL-8 vs WL-2) produced an extra 611 kg of
milk. Significant (P<0.05) differences between QL-8 and the other treatments occurred in 0-150
days of lactation. No significant difference in milk production was observed between WL-2 and
HL-4. Significant differences (P<0.05) were observed on live-weight changes of animals in QL-8
than cows in the other treatments in 0-75 days of lactation. Cows in WL-2 and HL-4 had a
negative live-weight change, -379 and -162 g/day, respectively, while live-weight change of cows
in QL-8 was 187 g/day. There was a general improvement of the body condition scores through
the lactation period for all treatments. Cows on QL-8 had significantly (P<O.05) fewer days-open
(79.7) compared to 98.7 and 106.3 for HL-4 and WL-2 respectively. Services per conception were
similar for all treatments.
The study demonstrated that it is possible to extract 611 kg of extra milk per cow's lactation by
reallocating concentrate during the first 12 weeks after calving at 8 kg/day. The study also
showed that concentrate feeding can be withdrawn altogether for the rest of a lactation period | en |
