This study was done to establish in vitro culture system of sheep oocytes. Sheep oocytes were recovered from ovaries by three methods : aspiration by 5 ml-syringe with 18 G and 21 G needle and scoop with a small spoon from incised follicle by a scalpel. Number of oocytes collected by aspiration with 18 G and 21 G needle and follicle incision were 3.7, 5.1 and 12.3 per ovary, respectively. Rates of oocytes with thick and compact cumulus cells were 67.2% (182/271), 91.7% (233/254) and 91.2% (571/626), respectively.
In vitro matured oocytes were inseminated with sperms treated with heparin for capacitation, and cultured for cleavage in TCM 199 added bovine serum and modified SOF added amino acids. The cleavage rates in TCM 199 and SOF were 76.4% and 60.4%, respectively (P<0.05). But the development rates to blastocyst were 6.6% (7/106), 17.7% (17/96) and hatched were 1.9% (2/106) and 10.4% (10/96), respectively (P<0.05).

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To estimate the basal water requirement for sheep, water balance was studied using 12 sheep fasted for 8 days. The balance was determined for the last 3 days at fasting. Mean values for fasting heat production, drinking water intake, metabolic water, water excreted in urine, water lost through respiratory evaporation and water debt were 226±40kJ/kg^0.75, 18.5±21.5g/kg^0.75, 6.1±1.2g/kg^0.75, 30.4±17.2g/kg^0.75, 14.1±3.3g/kg^0.75 and -22.9±20.0 g/kg^0.75, respectively.
Fasting heat production was positively correlated with drinking water intake, metabolic water and water lost through respiratory evaporation (P < 0.01). Drinking water intake was correlated with water excreted in urine and water lost through respiratory evaporation (P < 0.05). Drinking water intake, metabolic water and water lost through respiratory evaporation were estimated to increase 25.6, 2.87 and 6.46 g/kg^0.75 per 100 kJ of fasting heat production, respectively. The basal water requirement for sheep was estimated to be 43 g/kg^0.75. Water drinking was suggested to be insufficient to satisfy this requirement because of inhibition of thirst by some process of the water absorption in the intestine.

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Relationship between the frequency of a ewe's urination and the sniffing and mounting behavior of a ram during estrous cycle was examined. The first day on which mounting behavior occurred was standardized as day 0. All ewe and ram behavior was recorded from day-9 to day 5 and analyzed. The frequency of urination increased from day-1, and on day 0 it occurred more than on any other day (p<0.05). The frequency of flehmen showed the same pattern of urinating, and that of flehmen to ewe's urine occurred at a constancy rate (37%). On the other hand, though the number of nosings correlated with those of flehmen and urinating, the peak occurred on day-1. And also, a ewe's urine was sprayed artificially towards rams isolated from ewes and rams' flehmen responses were investigated. As a result, there were no significant differences between the rate of a ram's flehmen to a ewe's estrous urine and that of non-estrous urine. These results were demonstrated that ewe's urinating behavior became the index of the estrous cycle. Furthermore, it was suggested that flehmen behavior have a function to monitor ewes' urine constantly during estrous cycle.

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This experiment proved that a long-term automatic recording of grazing and rumination behavior in sheep was possible by application of an ambulatory data-logger which made for cattle and house. Sheep grazed on pasture at 770 m above sea level showed a seasonal variation of grazing and rumination behavior. Results were as follows :
1) In spring, most of grazing behavior was observed in the daytime.
2) In summer, there was a large decrement in grazing time as compared with spring and autumn. Most of grazing was observed between 14 : 00 and 21 : 00 h, and short term grazing periods were observed at night and in the morning.
3) In autumn, grazing time at night increased as compared with that in spring, and no grazing period was observed about sunrise.
4) There was no difference in rumination time among spring, summer and autumn. The ratio of rumination time to grazing time was 0.87 in spring, 1.52 in summer and 1.05 in autumn.

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Some aspects of the sucking behaviour of Suffolk lambs were recorded during their first hours of life. Observations were made at parturition on 8 single-and 14 twin-bearing ewes, all of which took place in indoor lambing pens.
The median times for first to attempt to stand, first to stand and first to attempt to suck were 10, 17-18 and 17-19 min after birth for all lambs respectively. The median time for first to suck successfully was 56-60 min for singles and second-born twins compared with 82 min after birth for first-born twins. The median time interval between the birth of the first and second lambs of a twin pair was 20 min, but this interval varied between 1 to 60 min. In the twins for which this interval was long, the attempt to suck by the first-born twin was sometimes interrupted by the ewe giving birth to another lamb.
It appeared that the first-born twin was not necessarily the first lamb to suck successfully.

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Twenty-two sets of Suffolk ewes and their lambs were maintained indoors for 120 days post partum. Seven ewes giving birth to twin lambs were grouped into two pens, and each set of twin lambs sucked its dam from birth until the group average time of 120 days (T-T). Eight ewes giving birth to twin lambs were grouped into two pens. In these sets of twin lambs, the larger one of each set was weaned at 60 days of age, and the other was left as a single lamb with the ewe (T-S). The lambs weaned at 60 days were grouped into two pens (T-W). Seven ewes giving birth to single lambs were grouped into two pens, and each single lamb sucked its dam from birth until 120 days of age (S-S). Ewes were fed formula feed for raising dairy cattle together with hay to meet the ewe's requirements for CP and TDN (NRC, 1985). T-S ewes consumed less formula feed than T-T ewes after 61 days of lactation. Lambs were creep-fed calf starter together with hay from 10 days of age. Formula feed gradually replaced calf starter from 56 to 60 days of age. From 61 days onwards, all lambs were fed formula feed of 1 kg on an as-fed basis per head per day.
The average live weight of T-T lambs reached 51.2 kg at 120 days of age. Hay intake in T-W lambs was higher (p < 0.05) than in T-S lambs, although T-W lambs had a lower (p < 0.05) average daily gain during 61 to 90 days of age. Average live weights at 120 days of age were similar between T-S and T-W lambs. Considerable variation (14%) between individual T-T lambs occurred in live weight at 120 days. A reduction in variation of live weight at 120 days was shown by T-S lambs (5%) and T-W lambs (8%). The average live weight of S-S lambs reached 45.6 kg at 90 days of age.
In Japan, lambs are slaughtered over a range of live weights varying from 43 to 53 kg. Lambs weaned at 60 days of age suffered a check in growth at weaning but recovered sufficiently to reach slaughter weight compared to that of twins left with ewes and twins sucking their dams. The technique of early weaning one of a pair of twins can provide a ready means of saving feed for ewes.

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The aim of the present study was to evaluate the effects of a single injection of follicle stimulating hormone (FSH) combined with pregnant mare serum gonadotropin (PMSG) on the ovulation and recovery rates, and normality of recovered embryos during the non-breeding season, and to compare the fertilizability of recovered embryos following artificial insemination (AI) into the cervix with fresh-diluted and the uterus with frozen-thawed semen by laparoscopy. In addition, plasma estradiol-17β (E₂) and luteinizing hormone (LH) concentrations were measured to characterize the hormonal responses in the simple superovulatory treatment.
In spring 1995, 17 crossbred ewes were treated with MAP sponge for 12 days. Two days before sponge removal, superovulation was induced by a single injection of 20 mg FSH in combination with 500 IU PMSG. All ewes were inseminated into the cervix with fresh-diluted (Group A : n=8) or into the uterus with frozen-thawed semen (Group B : n=9) during 36-42 hr after sponge removal. In both group, the motile sperm concentration for insemination was at least 25×10⁷ spermatozoa. Moreover, E₂ and LH were measured in the six treated ewes. Ovulation rate was 15.9±2.1. All ewes except one ewe already showed an endogenous LH surge from 6 (the time of starting blood collection) to 10 hr after sponge removal, followed by a surge at 2 to 4 hr after GnRH injection. There were no significant differences on the proportion of fertilized (Group A : 23.5%, Group B : 17.0%) and normal (14.1% and 9.1%) embryos. There was also no significant difference in the proportions of fertile ewes (ewes yielding fertilized ova per ewe inseminated) between the two insemination methods (Group A : 50.0%, Group B : 66.7%). In this study, fertilization rates were low in both Al methods. It was considered that ovarian response was too sensitive with the combined hormonal treatment, and thus premature ova were ovulated, or that ewes were inseminated at the unappropriate time.

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[in Japanese]

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The palatability of the lamb meat of four different ages in months (4, 6, 8 and 12 months) were evaluated. The panel consisted of 40 girl students, aged 19.1. The meats (loin and ham) were evaluated, after dipping into the boiling water for 10-15 seconds (traditional cooking in Japan, called “Shabushabu”). The sensory evaluation was performed according to the method of Scheffe. The checking point were color, odor, tenderness, flavor and total point evaluations.
Results obtained were as follows; there was no significant difference on the desirable degree of the loin among four different ages. However, there were significant difference on color and odor of the ham. On the color, it was found that panels were separated to two groups of different preference, namely a group preferred the ham with faint color such as 4 age in months, while the other group preferred with deep color such as 12 age in months. On the odor of the ham, the youngest lamb was the most acceptable.

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To study effect of kinds of hay on serum cortisol concentration, five ewes were given seven kinds of hay such as sudangrass (SG), bermudagrass(BG), timothy (TI), prennial ryegrass (PR), oats (OA), Italian ryegrass (IR) and alfalfa (AL) hays, ad libitum. Serum cortisol concentration was determined on the 1st, 7th and 21st days when each hay feeding was commenced. The relationship between serum cortisol level and dry-matter intake (DMI) and time spent for eating and ruminating was investigated. Results were as follows : 1) DMI for AL was the greatest, that is 1.42 kg/day, and that for IR the least, that is 0.72 kg/day. Crude protein content of the hay significantly and positively correlated with DMI. 2) There was no significant difference in serum cortisol level among hays given to sheep. Serum cortisol level showed lower concentration on the 21st day than those on the 1st and 7th days for all hays except for BG. The serum cortisol level on 7th day significantly and negatively correlated with DMI. 3) With the consideration on changes in serum cortisol level, the palatability of hay diets was inferred to have a possible influence on the serum cortisol level of sheep.

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