الفهرس 
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Abstract
The current study was conducted to evaluate the effect of different protein sources with different degradability during two separate reproductive phases, flushing and late gestation, on fertility measurements, metabolic parameters, colostrum composition and lambs birth weight in Egyptian ewes.
Experimental design
The study was carried out through two separate phases. The first phase, flushing-first gestation, extended for three months one before mating and two months after. In this period the effect of protein degradability on the reproductive performance, rumen kinetics, ewes’ body weight change and blood metabolic status was tested. The second phase, late gestation, covered two months before lambing season and feeding continued for one week after. In this phase the effect of protein degradability on colostrum composition, and its IgG concentration, body weight change of dams and birth weight of their lambs was studied. The first and second phases were separated by one month of the Institute farm feeding.
Thirty-five multiparous nonpregnant native crossbred ewes (Barki x Rahmani), aging between 2 and 3 years, with a body condition score (BCS) between 2.5 and 3.0, and body weight of 50±5 kg were used. Experimental ewes were randomly allocated to five dietary treatments (7 ewes / treatment). In diet I (control), solvent extracted soybeans (SESM 33% RUP of CP), II feed grade urea (FGU 31% RUP), III slow release urea (SRU 31% RUP). As sources of undegradable protein, extruded expeller SBM-EESM 40 (37% RUP) and extruded expeller SBM-EESM 60 (41% RUP) were used in groups IV and V, respectively. The other feed ingredients in the mixed diets are alfalfa hay and wheat straw, as roughages, and yellow corn and molasses in addition to the supplements as concentrates. The diets formulated were intended to be the same in CP for the two periods, at the higher levels, to keep the same nutritional circumstances for the ruminal bacteria. The ME reached about 2.2 Mcal/kg DM diet and the CP 12 – 12.5 %, levels which nearly satisfy the requirements for ewes carrying twins, if any. The estrous cycles of the ewes were synchronized using an intravaginal sponge containing 60 mg of medroxyprogesterone acetate inserted for 14 days at the start of the experiment.
During the experimental period, the experimental total mixed rations and feed ingredients were sampled for chemical analysis and determination of the in vitro nitrogen degradability characteristics. Blood samples were collected from ewes to test biochemical and hormonal analyses, as well as ruminal fluid, was sampled in the last week of the first period. The body weight change for the experimental ewes and their lambs’ birth weight were registered and the amount of food consumed was recorded. In addition, colostrum samples were collected immediately after lambing to estimate its composition and IgG levels.
Results
Flushing period
Regarding daily feed intake, crude protein, and metabolizable energy levels of intake, neither protein sources nor an increase in the level of dietary RUP had an effect on feed intake. As long as the control group with a diet of 33% RUP of CP equalled EESM 40 with a diet of 37% RUP and surpassed EESM 60 with 41% RUP.
As to the body weight change, ewes fed a 37% RUP (EESM 40) diet gained more (p<0.05) weight compared with ewes fed a 31% RUP (SRU) diet (6.71 vs. 2.92 kg) with significant difference.
Reproductive indices were represented by three rates, pregnancy, lambing and fertility and another percentage the twinning one. Lambing rate is 100 % in all groups while the twinning percentage was the highest in EESM40 (50 % and one ewe born triplet) compared with the other groups ranging from 0 to 25 %. While the urea groups had the highest fertility rate. So it seems that the pregnancy rate and fertility one are not affected by the supply of RUP, on the reverse it was the highest in urea supplements containing nearly no RUP.
Regarding ruminal fluid parameters, the overall post feeding pH values, the lowest pH was in the EESM groups, and the other three groups are equal. Ruminal ammonia in the five groups post feeding were equal in SRU, EESM 60, and control and ranged from 8.82 to 7.94 mg/100 ml, while, it increased to 10.04 mg in EESM 40 and even more to 11.83 mg in FGU. The TVFAs in mequiv / 100 ml in the five groups post feeding ware equal in control, EESM 40 and EESM 60 and ranged from 14.22 to 15.19, while, it decreased to 12.69 in FGU and even to 9.52 in SRU.
The VFAs were found to be mostly composed of acetic acid reaching from 59.62 to 64.71 % and followed by the propionic at from 21 to 23 % with no differences between groups. The butyric acid was only from 9.97 to 12.64 % with the highest ratios in EESM 60 and EESM 40. Isobutyric varied from 0.66 to 2.64 % with the lowest figures in EESM 40 and SRU. The valeric varied from 0.93 to 2.95 % with the lowest figures also in EESM 40, 60 and SRU. Isovaleric reached less than 1 % except in FGU it reached 1.38. In conclusion the acids are mostly acetic about 64% and propionic about 23 % and the rest is mostly butyric and isobutyric reaching about 11 %, and EESM40 group was the lower degree of degradation of branched chain amino acids.
Regarding serum progesterone levels, it is noted that all the three groups (control, FGU, and EESM 60) were statistically at the same levels allover the days of sampling (every 3 days during reproductive cycle), but the groups SRU and EESM 40 showed the highest ones.
Reviewing blood biochemical parameters, serum glucose concentration of the groups FGU, EESM 40 and EESM 60 were nearly equal 36, 36 & 39 mg/dl in order, while the group SRU was exceptionally high (57 mg) followed by the control (43 mg). In overall means of BUN, all groups were statistically equal (18 – 21 mg/dl) except EESM 60 group showed a lower urea N value (14 mg/dl) which can be attributed to its very high RUP concentration. Regarding total protein findings, in the overall means FGU, SRU, and EESM 40 were equal and the control and EESM 60 were of the highest equal levels. The five groups’ results of albumin were equal ranging from 2.6 to 3.5 g/dl with the two diets FGU and SRU had statistically high values. Regarding globulin concentrations the control and EESM 60 were the highest (6.89 & 6.60 g/dl) while the rest of the three groups FGU, SRU, EESM 40 reached in succession to 4.41, 4.66 & 5.22 g/dl.
Late gestation period
In the present study, there was no clear effect for the different supplements and different ratios of RUP on the levels of feed intake, CP, or ME; the intakes were nearly equal with the surpassing of the control group, followed by EESM 40. As to body weight change from zero to 2 wks pre-lambing ewes fed the 37% RUP (EESM 40) diet gained more (p<0.05) weight compared with ewes fed the 31% RUP ( FGU) diet (5.62 vs. 2.5 kg). In the body condition scores the least group got affected by gestation was EESM 40 where BCS change is - 0.01 followed by the other four groups which nearly equate with each other as the BCS changes ranged from – 0.37 in EESM 60 to – 0.50 in the control.
As to the lamb birth weight, there was no significant difference of high level of RUP on lambs’ birth weight, especially the EESM 60, which showed a weight that did not differ so much from the weight of the low or zero level of RUP, the FGU and SRU groups. EESM 40 was the twins and triple-bearing group, and this might be reflected in their lowest lamb’s birth weight.
Regarding colostrum composition, it is noted that EESM 60 is the highest in fat, protein, TS, SNF, and immunoglobulin G (IgG) and the lowest in urea N. Also, the FGU group is the lowest in fat, protein, TS, SNF, and salt and the highest in urea N. from the colostrum analysis point of view, the EESM 60 diet is nominated and the FGU diet is excluded.
As to the findings of blood biochemical parameters for all treatments. Acetone was similar in all groups (4.66–4.91 mg/dl), so it can be concluded that the four supplements of protein have no effect on acetone, although the high RUP group EESM 60 tends to decrease. In the overall mean of glucose concentration all the five groups were statistically equal and ranging from 53.18 in EESM 40 to 62 mg/dl in SRU. Regarding blood urea N, the overall means; SRU & EESM 40 the highest (23.33 & 22.63 mg/dl) and EESM 60 (12.73 mg/dl) the lowest. There is no clear reason for the equality of SRU diet (31% RUP) and EESM 40 (37%), while it is of advantage for the EESM 60 to be the lowest allover the days and mean. As to the serum total protein, albumin and globulin the groups were statistically equal without any significant effect for the diets. The current study showed that supplementation with different levels of RUP to ewes during late pregnancy did not affect their IgG levels.
Conclusion
In conclusion, the current study findings suggest that for ewes with a good body condition score (BCS 3.0), in terms of ewe performance, reproduction, colostrum constituents, and the weight of their lambs at birth, adding different protein sources or raising the RUP content in the diet had little impact. The parameters measured show superiority in certain groups and a lack in others. Accordingly, it is clear that the highest and low levels of undegradable protein are equal. from the economic point of view, the level of 31 % RUP (FGU) was the best followed by the group of EESM 40 (37% RUP) then the group of SRU. The level of 33% RUP in the control and even 31% in FGU and SRU were sufficient as long as the dietary protein percentage was not less than 12 %.