University of California, Davis

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1 EFFECT OF VITAMIN D AND OF SHEARING ON EWE LAMBS D G. M. SPURLOCK, D. T. TORELL, B. McGowAN, W. C. WEIR AND G. E. BRADFORD University of California, Davis URING the usual winter in the Coast Range of California the skies are overcast with fog and clouds a large proportion of the time; the sun is low on the horizon, and the ultra violet light rays are relatively weak. Since sheep are commonly shorn in the spring months they pass the winter in fairly long fleeces and are almost completely covered with wool. It would appear that under range conditions sheep in this area not having access to suncured hay might have marginal or submarginal vitamin D intake. Experimental work by Fitch (1943), Ewer and Bartrum (1948) and Grant ( ) has shown that under New Zealand winter conditions hoggets (weaned lambs) are subject to rickets while being carried on green pasture. These workers have demonstrated that high carotene content of green growing forage interfered with utilization of marginal intake of vitamin D, thus producing rickets in the lambs. The early administration of large quantities of vitamin D by mouth has been effective in preventing rickets in New Zealand lambs. While rickets has been uncommon in Coast Range lambs, it was considered possible that a subclinical avitaminosis D might exist in the area. Therefore, this experiment was undertaken to measure the effects of vitamin D supplementation and shearing date on ewe lambs. Procedure Two hundred ewe lambs at the Hopland Field Station were included in the trial. These lambs were of mixed whitefaced type but with Corriedale breeding predominanting; they were born during January and February of Because of mortality during the early part of the experiment, complete data were gathered on 193 lambs. These lambs were in a feeding experiment from July 16 to December 2, 1957 in which different feeds were being compared for their value as supplements to range forage. In that experiment the lambs were divided into six groups which received the following supplements: (1) none (control); (2) pelleted alfalfa cut in the full bloom stage; (3) pelleted alfalfa cut in the bud stage; (4) a mixture of equal parts cottonseed meal and barley; (5) cottonseed meal alone and (6) barley alone. Groups 2 to 6 received ~ lb. per head per day of the supplement fed six days per week. Starting August 16, 1957 the experiment on vitamin D and effects of shearing was combined factorially with the feeding experiment noted above. For this purpose the animals were allotted within feeding test groups 1250

2 VITAMIN D AND SHEARING 1251 into six sub-groups on the basis of sire, dam shearing weights for 1956, type of birth, and body weight. The result was six groups of animals treated as follows: Groups I (34 lambs) and II (31 lambs) were shorn on August 16, 1957 and again on April 28, Groups III (33 lambs) and IV (31 lambs) were shorn on March 10, 1958 and again on April 28, Groups V (32 lambs) and VI (32 lambs) were shorn on April 28, All lambs had been shorn previous to the start of the feeding experiment on May 5, Groups I, III and V received 1 million units of vitamin D by intramuscular injection on December 2, Groups II, IV and VI received no supplementary vitamin D. The animals were weighed July 16, 1957 and again at the end of the experiment (April 29, 1958) after a 12-hour overnight stand without food or water. Weights on a non-shrunk basis were taken at intervals throughout the trial. Blood samples were also taken for the determination of serum calcium and phosphorus on 10 lambs in each group. Fleeces were weighed from each animal at the various shearings and a side sample of approximately 100 gin. was bagged for shrinkage determination. The latter step allowed the calculation of clean weight of fiber for each animal at each shearing period throughout the trial. The weight gain and wool data were subjected to analysis of variance in which the effects of rations, shearing dates, vitamin D supplementation and the various interactions were considered. Results and Discussion The mean individual weight gains and clean vr production for the different shearing and vitamin D treatments are given in table 1. TABLE 1. MEAN INDIVIDUAL WEIGHT GAINS AND CLEAN FIBER PRODUCTION OF EWE LAMBS Total Weight clean wool gain, lb. production, lb. Experimental group Treatment No. of lambs July 16/57- April 29/58 May 5/57- April 28/58 I and II Shorn Aug. 16, 1957 and Apr. 28, III and IV Shorn Mar. 10, 1958 and Apr. 28, V and VI Shorn Apr. 28, I, III and V 1,000,000 I.U. vit. D on Dec. 2, II, IV and VI No vitamin D

3 1252 SPURLOCK ET AL. In the analysis of the data on gains none of the treatment effects or interactions were significant, although the effect of shearing date approached significance (the August-shorn lambs gained more). The supplementary rations fed during the early part of the trial (July 16 to December 2, 1957) did not significantly affect gains over the period July 16, 1957 to April 29, The maximum difference was between the cottonseed meal group and the controls and amounted to 5.7 lb. The gains of the various groups are in approximately the same order as those of the clean fleece weight which do differ significantly. In contrast to the effect on clean fiber weights any earlier effect of supplementation on body weight was largely overcome in the different groups of lambs at the final weighing date on April 29, The lack of response to vitamin D injection under these conditions suggests that the ewe lambs were receiving a sufficient amount of the vitamin in range feed or from exposure to fulfill any need, and that the daily level of carotene intake was insufficient to interfere seriously with vitamin D utilization. The injection of vitamin D lowered clean fleece production significantly (P~.05). The difference between treated and untreated lambs was 0.27 lb. of clean fiber. The reason for this is unknown, but it may indicate that the harmful level of vitamin D was closely approached at the dosage given. Shearing in August and again in April increased clean wool production as measured by wool shorn compared to shearing in April alone (P~.01). The shearing data means were: August, 7.07 lb.; March, 6.12 lb.; and April, 6.10 lb. March shearing and reshearing in April had no effect as compared to April shearing alone. The increased wool production of the fall-shorn group indicates that the animals in shorter fleece were better able to grow or retain their wool until shearing time. Why this is so is not clear, though sheep producers recognize that animals in short fleece carry less water in their fleeces in stormy weather, that their fleeces dry out more quickly, are less susceptible to wool rot and staining, and finally that they lose less wool on brush than animals with long fleeces. Table 2 shows the mean plasma calcium and phosphorus of the sample ewe lambs bled from each experimental group. The differences in means between groups are small and are not indicative of any significant effect of treatments. Differences in means for all groups between dates could represent differences associated with such factors as activity or length of time of fasting before bleeding. The data show the range of these measurements for lambs kept under these range conditions. The different supplementary rations given to the lambs early in the experiment affected clean wool production significantly (P<.01). Barley did not increase wool production significantly (0.10 lb.) but cottonseed meal and barley (0.64 lb.), full bloom alfalfa (0.69 lb.), bud stage alfalfa (0.82 lb.) and cottonseed meal (0.98 lb.) all resulted in significant increases. This demonstrates again the well-known effect of nutrition on

4 VITAMIN D AND SHEARING 1253 TABLE 2. CALCIUM AND INORGANIC PHOSPHORUS CONTENT OF PLASMA OF EWE LAMBS ~ Mean Experimental group I II III IV V VI per date mg. % mg.% mg.% mg.% mg. % mg.% mg.% July 16, 1957 Number bled Ca , P Aug. 16, 1957 Number bled Ca P Dec. 2, 1957 Number bled Ca P Mar. 10, I958 Number bled 9 10 ll ca P Apr. 28, 1958 Number bled i0.8 Ca P YIean per group Number bled for total Ca period P a Clark and Collip's (1925) method for calcium and Fiske and Subbarow's (1925) method for phosphorus were followed in making determinations on plasma obtained from heparinized whole blood. wool production. None of the interactions in the analysis of the clean wool data approached significance. The winter at the Hopland Field Station was one of the wettest on record. The rainfall from December 2, 1957 to April 28, 1958, recorded at a somewhat lower elevation than that where the experiment was conducted, was approximately 45 inches. It appears that neither early shearing nor vitamin D injection gives sufficient practical benefit for ewe lambs under these conditions to make their use advisable. Summary Weanling ewe lambs on range forage were supplemented with different rations from July 16 to December 2, Lambs were allotted within different ration groups so as to include three groups of lambs each representing a different shearing treatment. On December 2, 1957 half of each shearing treatment group was given 1 million I.U. of vitamin D by intramuscular injection. Weight gains were compared over the period July 16, 1957 to April 29, 1958 and clean wool production over the period May 5, 1957 to April 28, LambS shorn in August and again in April showed a non-significant increase in weight gains (2.1 lb.) but a significant (P<.01) increase in clean wool production (0.97 lb.) compared to the group shorn in April alone. Shearing in March and reshearing in April was of no advantage compared to April-shearing alone.

5 1254 SPURLOCK ET AL. Vitamin D injection tended to decrease gain (not significant) and significantly (P<.05) lowered clean wool production, by comparison with controls. Earlier supplementary rations showed no significant effect on weight gains over the total period but did significantly (P<.01) affect clean wool production. Neither vitamin D injection nor early shearing was of sufficient benefit to weanling ewe Iambs to warrant use in one of the heaviest rainfall years on record in the Hopland area. Literature Cited Clark, E. P. and J. B. Collip A study of the TisdaU method for the determination of blood serum calcium with a suggested modification. J. Biol. Chem. 63:461. Ewer, T. K. and P. Bartrum Rickets in sheep. Australian Vet. J. 24:73. Fiske, C. H. and Y. Subbarow The colorimetric determination of phosphorus. J. Biol. Chem. 66:375. Fitch, L. W. N Rickets in hoggets, with a note on the aetiology and definition of the disease. Australian Vet. J. 19:2, Grant, A. B The role of carotene in ovine rickets. Proc. New Zealand Soc, An. Prod. 14:77. Grant, A. B Vitamin A and ovine rickets. Vet. Reviews and Annotations l(ii) :115.