|dc.contributor.author||Collins, Hilary Alexandra||
|dc.description.abstract||The objectives of the research were to: achieve a method of grazing species comparison in
which grazing behaviour would be unconfounded by stocking rate: to compare the
grazing behaviour of cattle, sheep and goats under equivalent pasture conditions: to
observe the interaction of animal species during periods of mixed grazing: and to define
grazing strategies which would fit the observations.
Three species of domestic ruminant (cattle, sheep and goats) were repeatedly observed
during progressive defoliation of temperate, ryegrass/white clover pastures at an equal
rate of disappearance of pasture mass (RDPM).
Eight grazing experiments were conducted, each for a period of between 4 and 21 days,
during winter, spring and summer. Animal intake was estimated from apparent
disappearance of pasture mass and faecal recovery, using Cr₂O₃ as a marker. Diet
composition and quality was measured in the extrusa (OE) obtained from oesophageal
fistulae of six individuals of each species.
RDPM was controlled at similar values across species (±13 kgDM/ha) in the range of
110-365 kgDM/ha/day over all experiments. It was concluded that RDPM was a
suitable, if laborious, method to compare intake behaviour.
Digestible organic matter intake (DOMI) of each species declined from a mean maximum,
ad libitum value of 48.7 (cattle), 40.0 (sheep) and 47.3 (goats) gDOM/kgw·75 at the
beginning of each experiment, to below 10 gDOM/kgW'75 at mean pasture masses (PM)
of below 1300 kgDM/ha for cattle and sheep and below 2000 kgDM/ha for goats. The
DOMI response was the result of a decline in both dry matter intake (DMI) and diet
digestibility (DMD) during the grazing period.
At PM above 1700 kgDM/ha cattle had a significantly (p<0.05) higher DOMI (29.7
gDOM/kgW.75) than sheep (19.7 gDOM/kgW.75). Goats were intermediate (26.1
gDOM/kgW.75). Cattle also had the lowest rate of decline of intake (RDI) in the first half
of a grazing period (6.6%/day cf. 13.6% and 10.1% for sheep and goats respectively) and
were thus termed the most tolerant of the species. Overall, goats were the least tolerant
of pasture disappearance.
In summer pastures, green material was consumed in greater quantities by sheep (total
160 gDOM/kgW.75) than by cattle (113 gDOM/kgW.75) or goats (107 gDOM/kgW.75).
Clover was present in greater proportions in OE of all species than in the pasture being
grazed (by +7.9% (cattle). 41.7% (sheep) and 24.1% (goats). The similarity between OE
composition and composition of pasture was 0.76 (cattle). 0.58 (sheep) and 0.71 (goats).
Composition of cattle OE was more similar to that of the entire pasture than to any
particular horizon in the pasture. Composition of sheep OE was most similar to that of
the pasture horizon between 40 and 80mm above the ground and that of goats most
similar to the herbage growing above 8Omm.
Mixed grazing of cattle with either sheep or goats increased DOMI of sheep (10.7%) and
goats (43.0%). decreased DOMI of cattle grazing with sheep (18.7%: competition) and
increased DOMI of cattle grazing with goats (24.4%: complementarity). These
interactions were of sufficient magnitude to account for the animal production
differences observed in previous mixed grazing research.
Likely grazing strategies were postulated for the three species in which primary
motivations were defined as maximisation of intake mass (cattle). maximisation of intake
quality (sheep) and maximisation of intake of fresh growth (goats). The observed grazing
interactions of the species could be explained by reference to these strategies.||en
|dc.publisher||Lincoln College, University of Canterbury||en
|dc.title||Single and mixed grazing of cattle, sheep and goats||en
|thesis.degree.grantor||University of Canterbury||en
|thesis.degree.name||Doctor of Philosophy||en
|dc.subject.marsden||Fields of Research::300000 Agricultural, Veterinary and Environmental Sciences::300400 Animal Production::300403 Animal nutrition||en
|dc.subject.marsden||Fields of Research::300000 Agricultural, Veterinary and Environmental Sciences::300400 Animal Production::300406 Animal growth and development||en
|lu.thesis.supervisor||Nicol, A. M.||
|lu.contributor.unit||Department of Agricultural Sciences||en
|dc.rights.accessRights||Digital thesis can be viewed by current staff and students of Lincoln University only. Print copy available for reading in Lincoln University Library. ||en