Research Results - (PDF, 101 mb) - USAID

Table 7. Daily forage intake of grazing sheep
expressed on an organic matter basis (g OMI/
day), %body weight (%BW), metabolic body
weight (g/kg BW7 Th ), and as related to available
forage (g OMI/kg DM).
Month %BW
Jun. 2.5
Jul. 4.5
Aug. 2.2
Oct. 3.3
Nov. 3.7
Dec. 3.2
Jan. 3.8
Feb. 5.1
Mar. 3.3
Average 3.5
g/kg BWOT5
67
119
58
87
96
86
100
127
86
92
Sheep may be deficient in energy and
crude protein during gestation and early lactation.
Stocking rates for sheep in Peru are
based on grazing trials and an accepted intake
of 2% BW. As stated before, ewe equivalents are
used as standard stocking units in Peru. In the
Puna, Arturo Florez determined a stocking rate
of two ewe equivalents (e.e.) per hectare per
year was satisfactory for animal performance
and range forage production on good condition
rangeland. Other studies supported this stocking
rate in terms of range forage productivity.
Using the concept of 60% utilization of total
herbage, they recommended a stocking rate of 1
to 2.5 e.e./ha, depending on site productivity.
From our average herbage production of 2010
kg DM/ha, 60% forage utilization, and estimated
average intake of 1.4 kg DM/day, stocking
rates should be 2.0 to 2.4 e.e./ha per year.
This is in agreement with the conventional
stocking rate of 2.0 e.e./ha per year for this
region.
2. Influence of Improved Forages
Sheep. We studied the influence of
improved nutrition using cultivated pastures at
breeding and during late gestation and early
lactation for three years in the central Andes. In
contrast to ewes grazing native pastures, ewes
grazing cultivated pastures for seven weeks
prior to breeding had a greater (P < .05) percentage
of lambs born. Lambs born to ewes that
grazed cultivated pasture during the last trimester
of gestation and early lactation had higher
birth weights (P < .05), weaning weights (P <
.05), and average daily gain (P < .05) than did
lambs in the other treatments. The nutritional
influence of grazing cultivated pasture was not
important during late gestation and early
lactation, which coincides with the late dry
season. Strategic grazing of cultivated pastures
is most beneficial during critical periods such as
early lactation that overlap with the latter
portion of the nutritionally stressful dry season
(Table 8).
Table 8. Reproductive performance of ewes and lamb weights under three grazing treatments in
the Peruvian Andes
Item
Lambs born, %c
Net lamb crop, %f
Lamb birth wt, kg
Lamb weaning wt, kg
Lamb ADG, g
Breed Trilac Range SE
101 99d 880 3.2
89d 4.l
8 8 d 75e 3.1
a 4.4e 3.9d .15
24.6d 26.8e 23.4d 1.0
152.2d 167.1e 145.9 d 7.4
aTreatments were as follows: Breed is 7-wk access to cultivated pasture prior to, and for 4 wk after,
breeding; Trilac is '0-wk access to cultivated pasture including 7 wk at breeding, plus 6 wk during
late gestation and 7 wk after parturition; Range is grazing only native range yearlong.
bAs a percentage of ewes exposed to rams.
cMeans in the same row with different letters differ (P