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A program of controlled year-round sheep breeding, designed to provide batch lambing every 2 months, was evaluated on a private property in the Central Tablelands of New South Wales, over a 16-month mating period commencing in October 1977. It was preceded by a preliminary test designed to evaluate the use of pregnant mare serum gonadotrophin (PMSG) in conjunction with intravaginal progestagen sponges in the breeding season, and the importance of mating strategy. A flock of 140 Border Leicester x Merino ewes-of which 132 survived to the end of the test (mean 136)-and 6 Poll Dorset rams were used. Mating, pregnancy diagnosis and lambing were scheduled in advance using synchronization and induction of oestrus with intravaginal (i/v) progestagen sponges and PMSG (400 or 600 i.u.), pregnancy diagnosis based on plasma progesterone assay at 18 days after mating, and induction of parturition with either dexamethazone (DM ; 16 mg) or oestradiol benzoate (ODB; 20 mg). Treatment of a batch of ewes commenced every 60 days, and ewes diagnosed non-pregnant from the previous batch were included. Synchronized oestrus was induced 90 days after lambing, immediately after which lambs were weaned. There were eight lambing batches involving 365 treatments, which resulted in 219 lambings (60%) and 346 lambs, of which 321 survived to 72 hours, an average of 27 lambings and 40 viable lambs/2 months. The annual production rate was 176 viable lambs per 100 ewes.

SUMMARYThe value of the symptom pattern in achieving an accurate diagnosis in dyspeptic disease is still controversial. A number of investigators have used it to distinguish those patients who are at a high risk of serious disease (ulcer or cancer) from those who are not. Such findings have important implications for patient management, both in clinical and economic terms.

A factorial test is described, involving 1104 ewes, in which was studied the effects on lambing performance of (a) the inclusion of oestradiol-17G (0, 10, or 50 g) in Cronolone-impregnated sponges, (b) two doses of Cronolone, (c) treatment for 12 or 16 days, (d) insemination on detection of oestrus or on a fixed time basis, and (e) one or two inseminations. Both dose levels of oestradiol delayed the time of onset of oestrus (P < 0.05) but did not affect its incidence. The higher dose resulted in a 7.4% reduction in the lambing percentage (P < 0.05). Dose of Cronolone (P < 0.01) and duration of insertion of sponges (P < 0.10) affected the time of onset of oestrus but did not affect the percentage of ewes which lambed. Two inseminations half a day apart increased the lambing percentage by 11 .4 %. The optimum treatment - use of sponges impregnated with 30 or 50 mg Cronolone alone (i.e. without oestrogen) followed by two inseminations of all ewes at fixed times relative to withdrawal of sponges - resulted in lambing of 61 .8 % of ewes which received such treatment. It is concluded that this is the best available estimate of the potential of this treatment when used on a large scale.

The effect on fertility of the amount of Cronolone (Searle) absorbed from intravaginal sponges and the method of artificial insemination was studied. A significant linear relationship exists between fertility and the amount absorbed in 16 days, over the range 1-10 mg. No such relationship can be demonstrated above this amount, and great variability and sensitivity to failure of fertility is shown at all dose levels. Insemination on a fixed time basis is superior to that on teasing. Of ewes inseminated on a time basis on the second or third day after withdrawal of sponges, 117 lambed of 237 treated (49.4%). Of ewes inseminated on detection of oestrus, 97 lambed of 196 in oestrus (49.5 %) of 249 treated (39 .O %).

A number of treatments were used in association with Cronolone (Searl)- impregnated intravaginal spones in ewes which were artificially inseminated. Five factorial tests were conducted, involving 4880 ewes. Supplementary oestrogen (25 oestradiol benzoate) or androgen (1 mg testosterone) given at the time of withdrawal of sponges after 16 days' insertion was of no benefit. Few extra ewes exhibited oestrus and fertility was lowered. Flushing the vagina with a mild disinfectant at the time of withdrawal of sponges had no advantage. Ewes came into oestrus earlier, but fertility was not improved. Factors in the tests which did affect fertility were: (a) amount of Cronolone absorbed, (b) time of onset in ewes inseminated on detection of oestrus, (c) time of insemination relative to time of withdrawal of the sponge in ewes inseminated on a fixed time basis, and (d) number of spermatozoa used in the inseminate. There also was an interaction between dilution of semen and number of spermatozoa in that high fertility was associated with maximum number and minimum volume (maximum density and number). Insemination once with 600 x l06 spermatozoa in 0.2 ml inseminate at fixed times of 36, 42, or 48 hr after withdrawal of sponges resulted in lambing in 50 % of ewes (60 of 120).

Analysis of data for 72 Aberdeen Angus cows and their calves revealed the following significant relationships. (1) There was an inverse relationship between the total pre-weaning liveweight increase of calves and the liveweight change of their dams during the first half of lactation (r = –0.486; P<0.001) but not during the second half (r = +0.005; N.S.). Good dams "milked the flesh" during the period of maximum calf growth. (2) This is a maternal characteristic, not caused by greater demand of greedy feeders. (3) Steers made greater bone growth than heifers at all times of the year although during store periods both sexes gained (or lost) liveweight at the same rate. (4) Cattle unsupplemented in the store period tended to catch up with supplemented animals in the spring. Even when all treatment effects, including supplementary feeding, were analysed out, there remained a significant negative partial correlation between gains in the store and the subsequent spring fattening period (r = –0.20, P=0.05). It is suggested that the relative immaturity of slow-gaining animals at the start of the fattening period accounted for their compensatory gain. (5) "Compensatory growth" appeared to be most strongly demonstrated by older cattle: those which did better in the store period entered the spring in an advanced store condition and their weight gains were high energy fatty tissues, as compared with the high protein, low energy gains of lean animals. (6) The above notwithstanding, there was a positive partial correlation between the total lifetime rate of gain and the rate in the 9 month store period (r = +0.371; P = 0.01) and in the 3 month fattening period (r = +0.557; P< 0.001) prior to slaughter.

(1) Results of large-scale insemination trials conducted in the autumn of 1960 and involving 1955 Merino ewes in two flocks of mixed ages are presented. (2) Three factorial tests were conducted. The effects on returns to service and lambing performance of semen diluents and rams were studied with fresh semen (test 1, 240 ewes) and semen cooled, transported, and used 3–5 hr after collection (test 2, 300 ewes). Test 3 (320 ewes) compared the effects of duration of storage (0, 24, 48, 72 hr), diluents (heated cow milk 1 : 2, egg yolk-glucose-citrate (E.Y.G.C.) 1 : 2), antibiotic additive (nil, penicillin 1000 i.u./ml), and rams (two). (3) Overall returns to service and lambing results to insemination over one or two cycles were: test 1-fresh semen, 28.2,68.1, 77.7% ; test 2-cooled transported semen, 31.2, 63.5, 72.0%. There were no effects of diluents or of rams on results for these tests. (4) There was a linear regression of percentage fertility on duration of storage (test 3, pooled data for all diluents and rams) with the following formula: y = 61.0 – 14.0x, where y = percentage of ewes lambing to a single insemination, and x = duration of storage in days. (5) There was a significant ram difference (P < 0.05) but it did not affect the slope of the regression. (6) E.Y.G.C. was more effective than cow milk (P < 0.01) and there was a significant interaction between diluent and antibiotic additive (P < 0.05). Penicillin increased the relative effectiveness of cow milk but not of E.Y.G.C. (7) There was a significant interaction between duration of storage and antibiotic ( P < 0.05). Addition of penicillin appeared to lessen the slope of the regression. (8) It is concluded that the maximum duration of storage of ram semen with present diluents is 24 hr, and even this will probably result in a loss of fertilizing capacity of about 15%.

(1) Results of large-scale artificial insemination of Merino sheep (2346 ewes) on a private stud are presented, together with data for seven factorial tests designed to determine effects on fertility, following insemination at one or two successive oestrous periods, of season of insemination, milk diluents, age of ewe, individual ram, and frequency of insemination within a single oestrous period. (2) Insemination in the autumn is more effective than in the spring (79.7 v. 54.7 % of inseminated ewes lambed to insemination over two cycles; P < 0.001). (3) Results for maiden ewes in autumn or spring are 15–20% less than those for older ewes (P < 0.05 to < 0.001). (4) Ewes inseminated with semen of rams producing semen of indistinguishable quality, as gauged by standard field methods, may differ in fertility at a single insemination (P <0.01), but this difference disappears if ewes which return are inseminated by semen of the same rams at the next oestrous period. (5) Dilution of semen to 1.4 with heated cow milk – skim or whole – does not depress fertility. (6) Ewe-milk diluent depresses fertility following a single insemination (68.6 v. 47.3%; P< 0.01). (7) Insemination twice in the one oestrous period may increase fertility by 8–9% (70.3 v. 60.9%; P, N.S.). Such an increase is not worth the additional effort. (8) Fertility with diluted semen is comparable with that reported from eastern and central Europe, provided that ewes are inseminated during the autumn.

Data are presented from a detailed factorial experiment conducted on a private property in the Western District of Victoria and involving 72 grade Aberdeen Angus cattle and their dams. The relative contribution to daily liveweight increase and economy of production of sex (steer v. spayed heifer), sire (stud v. grade bull), level of supplementary feeding (high v. moderate v. low), season of birth (autumn v. spring), and year of birth (1954 v. 1955 control v. 1955 stilboestrol-implanted) was determined. Season of birth (autumn>>spring, P < 0.001) was easily the greatest single factor affecting daily liveweight gain, carcass beef production per week, and cash value of beef produced per week, followed in order of importance by sex (steers>>heifers, P < 0.001), and level of supplementary feeding (high >moderate = low, P<0 .001). Quality of the sire had no demonstrable effect on any factor studied. Year of birth slightly affected cash value of beef produced per week (P<0.05), but only because of yearly price fluctuations. Interactions between the main variates were relatively unimportant, but the spring-born calf was much more dependent on heavy supplementary feeding than was the autumn-born. Economy of production was dependent on calving at the correct time (autumn) and the reduction of supplementary feeding to a minimum. The value of the factorial experimental design for field studies of this type is briefly discussed.

A multifactorial experiment using 576 lambs is described, designed to determine the potential value of oestrogen implants in the Australian fat lamb industry. Actions and interactions of age at implantation (5 or 9 weeks), type of oestrogen (hexoestrol or stilboestrol), dose (15 or 30mg), crossbreed (Border Leicester x Merino or Dorset Horn x Corriedale), sex (ewe or wether), and type of birth (single or twin) were examined. Owing to drought conditions nutrition was only moderate. Sixty-three lambs were lost. Mortality tended to be concentrated on 30mg-oestrogen, Dorset Horn x Corriedale, male lambs (P < 0.05). Oestrogen-treated lambs (15 and 30 mg) reached 75 lb liveweight 2.5 and 1.9 weeks earlier than untreated lambs (P < 0.001). Wether lambs grew faster than females (P < 0.01). Treatment reduced dressing percentage and carcass weight by 1.8 per cent. and 1.1 lb respectively (P < 0-001). The dose of oestrogen was unimportant but the deleterious effect of stilboestrol was greater than that of hexoestrol. Treated carcasses were downgraded (P < 0.001) and there was a highly significant interaction between sex and treatment (P < 0.001). Carcasses of ewe lambs were more seriously affected than those of wethers. Treated carcasses were longer in the leg (P < 0.05) and thinner in the loin and flank than untreated carcasses (P < 0-001). The general effect was seriously to delay maturity and market quality, with a reduction in weight of carcasses despite increased liveweight gains. It is concluded that oestrogen implantation is unlikely to have wide commercial application in fat lamb production in Australia.

A total number of 507 ewes were inseminated at the rate of approximately 100 per day for 5 days, in a factorial experiment with variables: rams (5), treatments (5), days of insemination (5), volume of semen (2). Treatments were: (1) control; (2) progesterone daily for 16 days, PMS on 17th, inseminated on teasing; (3) progesterone every 2 days, PMS on 17th, inseminated on teasing; (4) as for (2), but inseminated 2 days after PMS; (5) as for (3), but inseminated 2 days after PMS. The overall lambing rate was low (31-6 per cent.). There were significant differences between rams, treatments, and day of insemination. Relative infertility of one ram was related to high incidence of sperm with curled tails. Treatment effects were: (1) 40.8 per cent. of ewes lambed; (2) 33.7 per cent.; (3) 32.9 per cent.; (4) 30.2 per cent.; (5) 15.0 per cent. Insemination was less efficient on the first day. Volume of undiluted semen used (0.05 or 0.1 ml) had no effect.

The interactions between two planes of pre- and post-natal nutrition of grazing ewes and the level of fertility on: ( a ) birth weight of the lamb, ( b ) its subsequent growth rate, and ( c ) wool growth, were determined in 140 crossbred ewes (52 Romney Marsh X Merino, 88 Border Leicester X Merino). The effectiveness of pregnant mare serum gonadotrophin (PMS) , injected on the 12th to 14th day of the oestrous cycle, for raising fertility ' was also investigated. Romney cross ewes had commenced their breeding season before January 21, a t least 3 weeks earlier than Border Leicester cross ewes. They lambed correspondingly earlier. The overall lambing percentage was very high (139 per cent.). PMS had no significant effect. There was no breed difference. Low- and high-plane ewes gained an average of 20 and 54 lb respectively during pregnancy. The mean weight of the conceptus was 34 lb (twins 39 Ib, singles 25 lb). Hence low-plane ewes lost an average of 14 lb body tissue as compared with a gain of 20 lb by high-plane ewes. Mean birth weights of lambs - single and multiple pregnancies - from the two nutritional groups were indistinguishable. Lamb losses and lambing troubles were fewer in the low--plane group. There was no interaction of pre- and post-natal nutrition on subsequent lamb growth rate. Post-natal plane of nutrition, sex of the lamb, and number reared all had highly significant effects on lamb growth rate. There were also significant interactions between plane of nutrition of the ewe and number of lambs reared and sex of lambs. Wether lambs needed the best possible nutritional environment fully to exhibit their inherent superior growth rate over ewe lambs. Restricted feed intake either in pregnancy or in lactation reduced wool growth to approximately the same degree. Although birth and weaning weights were affected by the number of lambs born and reared, wool production of the dam was not affected.

Sixteen measurements were made on 240 intact export lamb carcasses, representing 12 weight-grade classifications of 20 each, with the object of determining measurements likely to be of value for the assessment of conformation. Six were immediately discarded as being of little value. The remaining 10, which included three probe measurements, were subjected to statistical analysis to determine linear combinations of measurements most convenient for discriminating between grades in each of three weight categories, namely, light (27-28 lb), medium (35-36 lb), and heavy (43-44 lb). The 10 measurements were length of leg ( F ) , depth of thorax (Th), thickness of loin (BC), thickness of flank (P), length of carcass (K), thickness of shoulder (Sh), width of shoulder ( W) , width of flank (E) , width of gigots (G), and twist (Z), with discriminating capacity roughly in that order. BC, P, and Sh were all estimates of muscle and fat obtained by using a probe, and results obtained compared favourably with overseas measurements made on the cut carcass. E, G, and Z had little or no discriminating capacity. Optimum discriminations between grades were given within each weight category by the following combinations of measurements: light - F, K, BC, Sh, P; medium - F, Th; heavy - F, K, W, P; overall - F, Th, BC, P. The groups of carcasses separated into clear weight and grade zones, and several trends were noticeable. The most important of these were: (i) grading of light-weight carcasses was highly subjective between all grades, as both conformation and fat cover were considered; (ii) grading of the top grades in heavier carcasses was more clear-cut and depended primarily on conformation; (iii) there was a tendency for heavier carcasses to be up-graded relative to light carcasses, owing to their heavier fat cover. In view of the fairly clear pattern that emerged from the statistical model used, it is suggested that a rounded form of a discriminant function, namely, Y' = 0.057F + 0.050Th – 0.097BC – 0.17P, might be a useful index of conformation for fat lamb carcasses of all weights particularly if used in the form: Conformation score = 250 – 10Y'.

Two groups (2 and 3), each of 112 stud Merino ewes, which were experiencing regular oestrous cycles, received daily injections of 10 mg progesterone for 16 days, in an attempt to synchronize oestrus and ovulation for artificial insemination. One group (3) received an additional injection of 500 i.u. pregnant mare serum gonadotrophin (PMS) the day after the final progesterone injection. Injections were staggered so as to bring between 15 and 20 ewes of each group into oestrus on each of six days, on which days approximately equal numbers of untreated oestrous ewes were inseminated (group 1). In group 2 (progesterone alone), 104 ewes were teased and inseminated within 4 days of the final injection, including 74 (71 per cent.) on the third day. Corresponding numbers of ewes for group 3 (progesterone-PMS) were 107, 96 (90 per cent.). Injection of PMS significantly advanced and improved the precision of time of onset of oestrus, and presumably of ovulation. Of 315 ewes inseminated in all groups, 265 received 0.10 ml undiluted semen; 33, 0.05 ml; and 17, 0.20 ml. There were no apparent differences in lambing rate. Ewes inseminated, ewes lambing, and lambs born were: group 1, 104, 58 (55 per cent.), 74 (71 per cent.); group 2, 104, 53 (51 per cent.), 64 (62 per cent.); group 3, 107, 61 (57 per cent.), 85 (79 per cent.); overall, 315, 172 (55 per cent.), 223 (71 per cent.). There were no significant differences between groups in the proportion of ewes which lambed, or in the twinning rate. Ewes in oestrus and inseminated 72 hr after the final injection of progesterone had a significantly higher lambing rate than did ewes inseminated a day later. It is concluded that progesterone, particularly if used in conjunction with PMS, is of value in synchronizing oestrus in the breeding season for precisely planned artificial insemination.

Data are presented from a factorial experiment on the effects of a number of management practices on live measurements of young growing Aberdeen Angus cattle. Sire and dam influenced most measurements, as did supplementary feeding. Season of birth and sex were the two most important factors affecting all body measurements. Year of birth had a slight effect. Correlation coefficients are presented for corresponding measurements of dams and progeny, and for liveweights and measurements at successive ages. Birth weight was highly significantly correlated with weaning and slaughter weights (r = +0.432, +0.504; P<0.001), independent of the sex effect on growth rate. Body measurements at 6 weeks had a fair predictive value for corresponding measurements at 32 weeks (pre-weaning) and 84 weeks (pre-slaughter). The growth curves of heart girth and width of hooks closely paralleled that of liveweight (r = +0.985, -0.982). Length and height measurements were less close, followed by cannon measurements and depth of chest. Width of head and round measurements were least well correlated with weight.Under conditions of nutritional stress, bone growth may continue little impaired, despite loss of liveweight. Birth weights, or weights at a fixed time shortly after birth, could have a useful predictive value in selecting cattle for high weaning weight and post-weaning weight-for-age under southern Australian conditions of husbandry.

Fifteen tests carried out at an average interval of 4 weeks for 14 months showed an annual rhythm in the proportion of spayed crossbred ewes which exhibited oestrus after an injection of 15.6 µg oestradiol benzoate (ODB) following a 12 day period of progesterone treatment. Reactivity was highest in late summer and early autumn and lowest in winter and early spring. The periods of minimum reactivity coincided with the periods of low environmental temperatures and low body weights. The significance of the annual rhythm is discussed with particular relation to the phenomenon of "silent oestrus". No similar rhythm was detected in the 7-aginal response to oestrogen.

Experiments are described in which progesterone was used alone and in combination with pregnant mare serum (PMS) in breeding Suffolk, Suffolk crossbred, and Romney Marsh ewes in anoestrus. While oestrus, presumably with ovulation, was induced in a high proportion of ewes treated with the two hormones in combination, lambing percentages were low. Of 20 Romneys treated, 18 were served, but only 5 held to this service. Comparable figures for Suffolks were: 20 treated, 18 served, 7 lambed. The crossbreds gave better results; of 6 ewes treated all were served and 5 lambed. There was some evidence that the conception rate was higher following a complete ovarian cycle. Factors which may be involved in this phenomenon are discussed.

Experiments are described in which progesterone was used alone and in combination with pregnant mare serum (PMS) in breeding Suffolk, Suffolk crossbred, and Romney Marsh ewes in anoestrus. While oestrus, presumably with ovulation, was induced in a high proportion of ewes treated with the two hormones in combination, lambing percentages were low. Of 20 Romneys treated, 18 were served, but only 5 held to this service. Comparable figures for Suffolks were: 20 treated, 18 served, 7 lambed. The crossbreds gave better results; of 6 ewes treated all were served and 5 lambed. There was some evidence that the conception rate was higher following a complete ovarian cycle. Factors which may be involved in this phenomenon are discussed.