The effect of pattern of protein intake and level of energy intake on the performance and nitrogen utilization of the ewe

Abstract

An experiment was carried out in which each of thirty-six ewes was offered one of six dietary treatments from the 30th to the 140th day of gestation. The treatments supplied two levels of metabolizable energy (ME) intake (128 and 116 kcal/kgW°' 76 /day) each at three patterns of protein intake, namely equal increments at 22 day intervals, equal decrements at the same intervals and a constant daily intake throughout. The protein intake patterns supplied a mean daily intake of digestible crude protein of 3-74 g/kg W°' 75 /day. Nitrogen balances were carried out on four ewes from each dietary treatment during the last 10 days of each 22 day period.Thirteen ewes randomly distributed on all dietary treatments were barren. Mean rate of live-weight gain in the pregnant ewes was 123 g/day compared with 66 g/day in the non-pregnant ewes and was not significantly affected by treatments. Lamb birth weights adjusted to the basis of twins were 3-83, 4-02 and 3-56 kg for the increasing, constant and decreasing patterns of protein intake respectively.' Within patterns of protein intake there were no significant differences in nitrogen retention between pregnant and non-pregnant ewes until after 90 days of gestation. Thereafter retention increased in the pregnant ewes offered the constant and increasing patterns of crude protein and remained constant in the non-pregnant ewes. During the same period the retention of both pregnant and non-pregnant ewes on the decreasing pattern decreased.The effects of both energy and protein intake on nitrogen retention in early and late pregnancy were assessed by multiple regression analysis. The results are discussed in relation to other recent findings.

Reproductive performance and protein utilization in pregnancy of sheep conceiving at eight months of age

“…The levels of protein intake on Treatments 1 and 2 in the present investigation fall within the range studied by Robinson and Forbes (1967) and Robinson et al (1970) in mature ewes. There was approximately a 40% higher level of nitrogen retention in the young pregnant females as compared with the mature ewe at 95 days pre-parturition with no differences at 5 days pre-parturition.…”

“…from before mid-gestation, whereas in pregnant mature ewes (Graham, 1964;Robinson and Forbes, 1967;Robinson, Fraser, Corse and Gill, 1970) nitrogen retention increased only after 90 days of gestation. from before mid-gestation, whereas in pregnant mature ewes (Graham, 1964;Robinson and Forbes, 1967;Robinson, Fraser, Corse and Gill, 1970) nitrogen retention increased only after 90 days of gestation.…”

“…The balance procedure and the chemical analysis of samples were similar to those used by Robinson, Fraser, Corse and Gill (1970). They were offered their feed in approximately two equal portions at 08.00 and 16.30 hr.…”

Changes associated with pregnancy and lactation in some extra–reproductive organs of the ewe

“…These workers found no difference in the digestibility of dried grass pellets during pregnancy or lactation, but the increase which they recorded in food intake during lactation was much less than in the present study, in which as would be expected from the findings of Blaxter & Graham (1956), the high food intake was associated with a reduced digestibility of dry matter. Robinson, Fraser, Corse & Gill (1970) also found no difference between pregnant and non-pregnant sheep with regard to the digestibility of crude protein or dry matter of the diet. As in the present investigation, they recorded a slight increase in nitrogen retention during pregnancy, but this was not statistically significant.…”

Observations on the effect of protein intake and stage of gestation on the proportion of urinary nitrogen excreted as urea in sheep

“…Using diets of varying protein content, Robinson Animals and diets & Forbes (1967) and Robinson et al (1970) showed Experiment 1 that nitrogen retention in the ewe increased appre-Twenty-four, 3-to 4-year-old Romney x Scottish ciably during the latter half of pregnancy. This im-Blackface and Romney x Swaledale ewes were provement in protein utilization occurred not only used.…”