The comparison of supplements for young calves grazing autumn pasture: a thesis presented in partial fulfilment of the requirements for the degree of Master of Agricultural Science in Animal Science at Massey University
Thirty two autumn-born calves (sixteen bull and sixteen
heifer calves) were used to compared the effects of alternative
supplements on performance, health, herbage intake and feed
efficiency of young calves.
1. Four bull and four heifer calves in each of four
blocks,which had previously received milk ad libitum,were
randomly allocated to each of the four treatments at 5-6 weeks
of age. The supplements of liquid milk, dry milk and
concentrates were calculated to provide 11.28 MJME
metabolisable energy (ME) (for ruminants) and 175 g crude
protein (CP) daily and were fed for 5 weeks. Supplements were
offered once a day and amounts eaten were measured. The
control group was weaned directly onto autumn pasture.
2. Calves were grazed in the same paddocks,predominantly
ryegrass and white clover,divided into four equal areas by two
electric wires. Individual paddocks were used in rotation for
4-5 days and calves offered a daily herbage allowance of
approximately 60 g DM per kg liveweight. After the
experimental period the calves were grazed on pasture together
in two mobs, bulls in one and heifer calves in the other, and
liveweights measured until about 33 weeks of age.
3. The DM intake of supplement and herbage by individual
calves were estimated indirectly using faecal markers (Chromic
oxide and Polyethylene glycol).
4. Calf growth rates at various stages were measured.
Feeding of supplements significantly (P<0.001) increased the
liveweight gains of young calves grazing autumn pasture
(control 257.1 g/d). Among the supplemented calves, calves
receiving liquid milk had a significantly (P<O.OS) higher
liveweight gain (653.6 g/d) than those supplemented with soya
bean concentrate (507.1 g/d) and dry milk (473.5 g/d).
Liveweight gain of calves after the supplemental period (10-33
weeks of age) were not significantly different between
5. There was no significant (P<0.05) difference between
the liveweights of supplemented and non supplemented calves at
33 weeks of age but that for calves given the dry milk
supplement was significantly (P<0.05) lower than those for the
other supplemented groups.
6. All supplements significantly (P<0.001) depressed
herbage DM intake of young calves. The depression of herbage
DM intake per unit of supplement DM intake (substitution rate)
for calves given dry milk supplement was significantly higher
than those for calves consuming soya bean and liquid milk
supplements. Total DM or OM intakes (g/d) of calves with soya
bean supplement were significantly higher than for the other
groups whereas there was no significant difference between
those for milk supplements (dry and liquid milk supplements)
and the non-supplemented calves.
7. Liveweight gain of calves during the supplemental
period (5-10 weeks of age) were positively correlated (r=0.76)
to the ratio of ME to CP intake (KJME/gCP) and amount of
supplements DM intake (r=0.65).
8 The ME in rations containing milk supplements were
estimated to have been used with greater efficiency for
growth (K ) than that from the soya bean concentrate or herbage
9 A number of unexplained complaints (eg. red urine, hard
faeces and swelling neck) were found in calves fed with dry
10 The use of markers (Chromic oxide and Polyethylene
glycol) to estimate food intakes of calves has potential as
judged by the results of this experiment.