Two slaughter trials were conducted with lambs to evaluate the effects on production and some rumen characteristics of the addition of low quality roughage (wheaten straw) and a high quality roughage (pelletized ground lucerne) to wheat grain diets. In the first trial one group of lambs was given a 1/1 mixture of whole wheat grain and chaffed wheaten straw and another chaffed lucerne hay ad libitum. Lucerne-fed lambs had significantly (P < 0.001) higher dry and organic matter intakes, grew faster and had higher levels of volatile fatty acids in their rumens than lambs offered the mixed ration, although there were no differences between rations in dry and organic matter digestibilities. The apparent nitrogen digestibility of the mixed ration was significantly (P < 0.001) lower than that of the lucerne ration. Of lambs offered the mixed ration, 46% had extensive lesions on the ventral wall of the rumen at slaughter, and these were associated with marked inappetence and loss in liveweight. In the second trial comparisons were made of diets consisting of lucerne (either alone or mixed with cracked wheat) and whole wheat grain + limestone. The effect of treating the lucerne with formaldehyde was also studied. There were no significant differences in carcass gain with the lucerne diets; parakeratosis developed in some animals on lucerne-wheat diets but did not affect productive performance. The animals offered whole wheat lost weight, two died of wheat poisoning, and several animals developed lesions on the rumen wall. _________________ *Part IV, Aust. J. Agric. Res., 26: 729 (1975).

Ewes and wethers with oesophageal fistulas were compared with normal sheep in several experiments over three years. The grazing behaviour, herbage intake, liveweight changes, and ability to bear and rear lambs were altered little by fistulation, provided fistulas were less than 5 cm in length and closure of the fistulas was good. This was so even at a relatively high stocking rate of G ewes to the acre. These findings infer that studies with fistulated sheep provide information validly applicable to normal sheep. Fistulas that allowed good closure control (<5 cm in length) did not always allow complete recovery of ingested material. However, with incomplete recovery representative diet samples were obtained. Sampling procedures for obtaining adequately representative diet samples for individual sheep, and for obtaining estimates of diet composition for flocks of sheep on different pastures were established. The routine that must be followed to avoid obtaining untrue diet samples is to sample sheep when they are accustomed to a pasture, without prior fasting, and at the time(s) of the day when sheep are normally grazing. An hour's sampling period will collect about l/l0th of the total daily intake and longer periods may cause rumen dysfunction. Pooling data from once-a-day samples for two successive days for an individual sheep seemed to give accurate values for the whole diet over those two days for sheep set stocked on pasture. Variation between-sheep, between-days, and within-days in the nitrogen and soluble carbohydrate content and botanical composition of extrusa samples was studied. The contribution of these sources of variation to total variation differed for different diet constituents. For nitrogen, between-sheep variation was greater than between-day variation but for soluble carbohydrates the position was reversed. Within-day variation was much the same as between-day variation in a constituent. The standard deviations of nitrogen and soluble carbohydrate contents and botanical composition were large and a true mean value for any of these parameters for a flock of sheep, could only be obtained by pooling data for several sheep on several successive days.

A number of observations have been made on 5-to 6-month old wether Hampshire sheep undergoing uninterrupted growth (36-2% gain in shrunk wool -free live weight over 58 days), undernutrition (a 21-7 % fall in body weight over 27 days) and then followed by compensatory growth (a gain of 62-2 % in live weight over 52 days).Sheep being underfed had increased, and compensating sheep had decreased, apparent digestibility coefficients of feed dry matter compared to control sheep. Sheep undergoing compensatory growth drank more water, ingested more food per unit body weight, laid down less body fat, more protein and retained more water in their bodies than did control sheep. Tritiated water allowed estimation of total body water with an accuracy comparable to other reports in the literature.Changes in the weight and in RNA-P and DNA-P content of anterior pituitary, thyroid and adrenal glands were measured. Sheep thyroid glands were examined histologically to assess relative TSH outputs and no significant differences detected.R a t bio-assay of cavernous sinus plasma for somatotrophin and ACTH activity was made on these sheep. Somatotrophin was detected, but experimental groups did not statistically significantly differ in relative potency (TJ.S.P. units/ml fresh plasma). Compensating sheep had. significantly lower plasma somatotrophin potency per unit empty body-weight values than did the underfed sheep.No ACTH activity was detected in the sheep plasma of the several groups. During severe undernutrition the anterior pituitary gland decreased in size, but not in cell numbers, and still elaborated somatotrophin. Decrease in body size tends to increase the ratio of circulating somatotrophin per unit body size and thus may facilitate, in a permissive manner, the enhanced growth rate of animals undergoing compensatory growth.Restitution and gain of body size by compensatory growth is accompanied by hypertrophy of the anterior pituitary gland. This gland, after compensatory growth, showed evidence of enhanced synthesizing capacity.TNTT? ODTTO' TTO' Nr ^n a P r e v i°u s report on the body composition of 1191 animals (pigs, sheep, cattle;Reid et al. 1968) Compensatory growth occurs when previously some results were given of an experiment whose under-fed animals are given more food. I t expresses objective was to study the effect of submaintenance itself, for a variable period, as an enhanced rate of energy intake on the body composition of sheep but gain compared to that of similar, but continuously detailed body composition and endocrine gland fed, animals and is commonly experienced by the data were not given. grazing animal. The physiological basis of compenDetailed body composition data on 30 sheep are satory growth is obscure. Wilson & Osbourne (1960) given in the present paper because, of all the conhave reviewed this subject.siderable number of dietary treatments imposed on i A G s 79

The body composition of eight Merino wethers was estimated from the tritiated water (TOH) space and live weight at intervals during a cross-over experiment in which they were fed to either maintain a uniform live weight (about 34 kg) or to lose and, later, recover live weight over a 17-week period. The diet was a pelleted mixture of lucerne and wheat.The multiple regression equations used for these estimates were established from the chemical analysis of 24 sheep, including six from the cross-over experiment, which were killed at intervals during these two feeding regimens. The inclusion of TOH space in addition to live weight in the regression equations decreased the standard error of the estimates of body water, fat and energy by two-thirds. Correction of TOH space and live weight for gut water did not increase the precision of the equations.Sheep which ate, during the first 4 weeks of the experiment, one-third of the amount of food required to maintain their original live weight, lost 16% of their weight and 30 % of their total body energy. This weight loss consisted of 45 % water, 39 % fat and 13% protein. It appeared that tissue was mobilized inefficiently to meet a sudden energy deficit.When food was offered ad lib. to these sheep after they had maintained a liveweight deficit of about 11 kg for 8 weeks, they regained their weight in 5 weeks but only 75 % of their energy deficit. This was due to the high content of water (60 %) and low content of fat (23 %) in the regained tissue.The sheep that lost weight and then recovered it were, over-all, about 86% as efficient in their use of food to maintain body energy and produce wool as the sheep that maintained their original weight. s P a ce by Panaretto (1964) also indicated a marked decrease in fat during underThe efficiency of sheep during periods of alternate nutrition, but Hight & Barton (1965) concluded that under-nutrition and recovery can be assessed only protein loss was of greater importance, if the accompanying changes in body compositionThe aim of the present work was to measure the are known. Most of the reported work has been done changes in body composition of sheep which underwith growing animals, but Robinson (1948), by dis-went a period of severe caloric restriction, were section, and Beames & Morris (1965) by chemical then maintained at a low live weight and finally analysis of mature animals slaughtered at different recovered when food was offered ad lib. and to cornlevels of under-nutrition found that fat was more pare their efficiency with that of sheep which mainseverely depleted than other tissues. However, the tained their original weight. The changes in the body large variation between animals prevented a quanti-composition of living sheep during the experiment tative interpretation of these changes. Estimates of were predicted from multiple regression equations the body composition of living sheep derived from which related composition to the tritiated water • Present address: Abbott Laboratories Pty. Ltd., (TOH) space and live weight...

IntroductimThe use of oesophageal fistulae in sheep as a technique for obtaining samples of the forage ingested by grazing sheep has been reported by Torell (1954), Bath et al. (1956), Cook et al (1958). Heady & Torell (1959 and Luick et al (1959) in the U.S.A., and by McManus (1960) and Hamilton et a Z ( 1960) in Australia. Lesperance et al. (1960) have described a method for oesophageal fistulation of steers.Mechanical closure of the fistula, when it is not in use, is a major problem. It may be attempted either by permanent cannulation or by the fitting of stoppering devices. Cook et a2 (1958) reported success in the use of permanent cannulae, but our experience has not supported their The purpose of this communication is to report upon 37 cases of oesophageal fistulation in sheep additional to those reported on earlier (Hamilton et al 1960), the use of "split" plug stoppers for improved closure of fistulae, and the field performance of some of these animals. There are few references in the Iiterature on the performance of fistulated sheep under field conditions. Materials and Methods findings. (a) sheepThe sheep comprised 27 Border Leicester ewes, one Southdown X Merino ewe and 9 Border Leicester X Merino Crossbred wethers. The ages were from 2 to 3 years, except one (E55) which was aged 9 months at the time of operation. All the Border Leicester ewes had been mated prior to fistulation. (b) FistulationFistulation was effected either by the "direct" insertion of a latex plug stopper into a fistula with the muscularis mucosae sutured to the skin margins, or by the "insert" technique wherein the muscularis rnucosue was left intact and the flanges