New Zealand Journal of Agricultural Research abstracts
Short-term ingestive behaviour of sheep and goats grazing grasses and
legumes
1. Comparison of bite weight, bite rate, and bite dimensions for forages at two
stages of maturity
Y. GONG1
J. HODGSON2
M. G. LAMBERT1
I. L. GORDON2
1AgResearch Grasslands
Private Bag 11008
Palmerston North, New Zealand
2Plant Science Department
Massey University
Private Bag 11222
Palmerston North, New Zealand
Abstract Bite weight, bite rate, and bite dimensions (depth,
area, and volume) were compared among six sheep and six goats individually
confined indoors in metabolism crates, grazing monoculture turves (41 x 27 cm)
of five grasses and four legumes at the vegetative and reproductive stages of
growth. Each sampling period was restricted to 12-17 bites. Leguminous swards
resulted in a greater overall fresh bite weight (1253 versus 994 mg fresh
matter (FM), SE = 41, P < 0.001) despite a shallower bite depth
(6.1 versus 22.1 cm, SE = 0.6, P < 0.001) compared with
gramineous swards. Animals also obtained a faster bite rate on legumes than on
grasses (28 versus 24 bites/min, SE = 0.8, P < 0.001). The
taller reproductive swards led to greater bite weight (1297 versus 920 mg FM,
SE = 37, P < 0.001), but lower bite rate than vegetative
swards (18 versus 33 bites/min, SE = 1; P < 0.001).
Consequently, short-term intake rate did not change significantly with
increased maturity (6.1 versus 5.7 g DM/min, SE = 0.2). Mean bite weight was
greater for sheep than goats on both vegetative (1282 versus 914 mg FM, SE =
92, P < 0.05) and reproductive legume swards (1514 versus
1301 mg FM, SE = 92, P < 0.1), and was similar between the
two species on vegetative grass (786 versus 771 mg FM, SE = 82) swards.
However, goats had substantially heavier bites on reproductive grass (1410
versus 1008 mg FM, SE = 82, P < 0.01) swards. When swards
changed from the vegetative to reproductive growth stage, intake rate of sheep
decreased (from 7.0 to 5.8 g DM/min, SE = 0.2, P < 0.05)
because an increase in bite weight was countered by a fall in biting rate,
whereas intake rate of goats tended to increase slightly (from 5.1 to 5.7 g
DM/min, SE = 0.2) as a result of an increase in bite weight and a relatively
small fall in bite rate compared with sheep. Sheep showed a greater tendency on
vegetative swards to penetrate into the canopy to take deep bites whereas,
except on reproductive grasses, goats were shallow grazers from the top
downwards. However, when tall, stemmy reproductive grasses were grazed, sheep
appeared to penetrate into the canopies to graze the leafy components, and
rejected seedhead and stalk components within the grazed area, whereas goats
were less selective and prehended mouthfuls of herbage which included rigid
stems occurring within the defined grazed area.
Keywords ingestive behaviour; bite weight; bite rate; bite
dimensions; sheep; goats; grasses; legumes; vegetative swards; reproductive
swards; indoor feeding
New Zealand Journal of Agricultural Research, 1996, Vol. 39:63-73
0028-8233/96/3901-0063 $2.50/0 (c) The Royal Society of New Zealand
1996
PDF file of entire paper: medium quality (934K); (scanned from paper original: notes about this process)
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