Characterization of Oestrous Induction Response,Oestrous Duration,Fecundity and Fertility in Awassi Ewes During the Non‐breeding Season Utilizing both CIDR and Intravaginal Sponge Treatments

The aim of this study was to investigate characterization of oestrous response, onset of induced oestrus, oestrous duration, fecundity and fertility in Awassi ewes treatment with intravaginal sponges and Controlled Intravaginal Drug Release (CIDR) devices in combination with pregnant mare serum gonadotropin (PMSG) under local environmental conditions during the non‐breeding season. A total of 62 ewes were divided into three groups. Group CIDR (n = 20) was treated with CIDR devices for 12 days and 400 IU PMSG was injected upon removal of the CIDR. For ewes in Group Sponge (SP) (n = 24), 30 mg fluorogestone acetate was administered to the sheep for 12 days and 400 IU PMSG was injected upon withdrawal of the sponge. Group Control (CON) (n = 18) served as a control group and received no treatment. Adult, intact and sexually experienced Awassi rams were introduced to all groups at the time when the intravaginal devices were removed. There were no significant differences in terms of oestrous response (CIDR: 90%, SP: 87.5%), time to onset of oestrus and duration of induced oestrus between the CIDR and SP groups. The oestrous response of treatment groups was significantly greater (p < 0.05) than in the control ewes. There were no significant differences in pregnancy (CIDR: 70%, SP: 70.8%), lambing (CIDR: 85%, SP: 79.2%) and fecundity rates between ewes treated with CIDR and those treated with sponges. However, pregnancy and lambing rates were significantly (p < 0.05) higher in ewes treated with CIDR or sponges when compared with those in the control group. It was concluded that it is possible to induce fertile oestrus, successful pregnancy and lambing with the treatment of either CIDR or intravaginal sponge in combination with PMSG in Awassi ewes during the non‐breeding season.     

Estrus Synchronization in Sheep and Goats Using Combinations of GnRH,Progestagen and Prostaglandin F2α

The objective of this experiment was to evaluate the effect of GnRH, progestagen and prostaglandin F_2α on estrus synchronization in sheep and goats. Sixty Awassi ewes and 53 Damascus does were used in the study. The experiment started at the beginning of the breeding season (June/July). The same treatments were applied to sheep and goats as follows: no treatment (CON), 14‐day progestagen sponges and 600 IU equine chorionic gonadotropin (S), gonadotropin releasing hormone followed 5 days later by prostaglandin F_2α (GP) and gonadotropin releasing hormone, progestagen sponges for 5 days and prostaglandin F_2α on the day of sponge removal (GSP). None of the ewes in the S group lambed from mating during the induced cycle. A greater lambing rate (p < 0.05) was observed in the GSP group compared with the CON and S groups while the GP group was intermediate. The number of lambs born per lambed ewe was similar among the CON, GP and GSP groups. However, the number of lambs per exposed ewe was greater (p < 0.05) in the GSP than the remaining groups. The induced cycle kidding rate was 77% for all treatments combined. Similar kidding rate were observed among treatments. The numbers of kids born per kidded and exposed doe from mating during the induced estrus were also similar among treatments. Greater numbers of multiple births were observed in the GP and GSP than in the S group. In conclusion, a combination of GnRH, progestagen sponges and PGF_2α can be effective in synchronizing estrus and improving fecundity in sheep and goats. Although the use of GnRH–PGF_2α was effective, the addition of progestagen sponges at the time of GnRH administration appeared to improve reproductive parameters.     

Improving the Reproductive Efficiency, Pregnancy Diagnosis and Monitoring the Resumption of Luteal Activity in Indigenous Damascus Goats

Seventy‐five female Damascus goats aged between 1.5 and 5.5 years were used to evaluate the effectiveness of the intravaginal sponges and prostaglandin analogue on oestrous synchronization and fecundity; to diagnose pregnancy and to monitor the resumption of the luteal activity. Females were divided randomly, during the breeding season, into three equal groups, S, P and C. Females in group S were fitted with sponges containing 45 mg of flugestone acetate (FGA) for 14 days and injected with pregnant mare serum gonadotrophin (PMSG) at the sponge withdrawal. Females in group P were given two injections of prostaglandin F2α analogue at 11‐day intervals, whereas females in group C (control) received no treatment. The results showed that there was a significant difference (p < 0.001) in oestrous exhibition between females in group S as compared with those in groups P and C, with means being 30 ± 10, 172 ± 115 and 217 ± 75 h for groups S, P and C, respectively. Kidding rates resulting from the first and all matings were 80 and 88, 52 and 88, and 68 and 80% for groups S, P and C, respectively. Fecundity rates were 215, 175 and 180% for groups S, P and C, respectively, with a significant difference (p < 0.05) between the S and both P and C groups. Using an ultrasound pregnancy detector performed on days 57 ± 3 after mating, positive pregnancy diagnosis was 93.3% and 100% for non‐pregnancy. Females in the control group showed functional corpus luteum starting in September. It is concluded that FGA sponges plus PMSG treatment could be successfully used to synchronize oestrus and improve fecundity; whereas prostaglandin treatment was not effective to synchronize oestrus. It is also concluded that pregnancy can be diagnosed accurately and successfully using an ultrasound pregnancy detector. In addition, ovarian activity in the Damascus goat in Syria resumes in September.     

Fertility of ewes given either melatonin or progestogen sponges

The administration of melatonin via intravaginal sponges is an effective method of advancing the breeding season in ewes. In the present study the fertility of melatonin-treated ewes has been compared with that of ewes induced to ovulate by conventional treatment. On June 25, 15, 15-month-old ewes (group 1) were given intravaginal implants containing melatonin in silastic tubing. On August 8, 13 similar ewes (group 2) were given Veramix sponges which were removed 12 days later, when they were given 500 iu pregnant mare's serum gonadotrophin (PMSG). Two intact raddled rams were introduced to the combined groups on August 21. The mean date of mating was September 3 +/- 1.5 for group 1 and August 21 +/- 0.2 for group 2 ewes. All the ewes in group 1 and 10 in group 2 (77 per cent) were mated. All the ewes were slaughtered approximately 50 days after mating and their reproductive tracts removed. The mean ovulation rates were 2.1 and 2.3 in groups 1 and 2, respectively. The results indicate that conception rates of 87 per cent and 61.5 per cent of ewes put to the ram were obtained in the melatonin-treated and PMSG-treated groups, respectively. At slaughter the melatonin-treated group were found to have a mean of 1.47 live fetuses per ewe put to the ram and the PMSG-treated group a mean of 1.08. It can therefore be concluded that melatonin implantation is an effective method for the advancement of seasonal breeding in anoestrous sheep, and that the fertility achieved is at least as good as that given by conventional progestogen-PMSG treatment.     

Evaluation of melengestrol acetate and equine chorionic gonadotropin for out-of-season breeding in sheep on Prince Edward Island

The purpose of this study was to compare the efficacy of a recommended protocol of oral melengestrol acetate (MGA) to intravaginal medroxyprogesterone acetate (MPA), with or without equine chorionic gonadotropin (eCG), for out-of-season breeding of sheep on Prince Edward Island. One hundred and twenty ewes were assigned to 1 of 4 groups in a factorial design and were treated with either an intravaginal MPA sponge or oral MGA. Ewes received either an intramuscular injection of eCG or a saline placebo at cessation of progestogen treatment. The reproductive performance was best for the MPA-eCG group, followed by the MGA-eCG, MGA-saline, and MPA-saline. Pregnancy rates of 66.7%, 43.3%, 31.0%, and 16.7%, respectively, and ratios of lambs born to ewes exposed to the ram of 1.17, 0.63, 0.52, and 0.23, respectively, were recorded for these groups. We concluded that, under the conditions of this study, the use of oral MGA resulted in fewer lambs than did the use of MPA sponges with eCG. Nonetheless, the use of MGA may be attractive to producers because it is less expensive and more convenient than the use of sponges.     

Sexual behaviour of yearling Awassi,Charollais × Awassi and Romanov × Awassi rams exposed to oestrousAwassi ewes

This study was conducted to evaluate the sexual performance of 10-month-old, ram lambs of different breed groups. Eight ram lambs each of Awassi (A), F₁ Charollais × Awassi (CA) and F₁ Romanov × Awassi (RA) breed types were subjected to sexual performance tests by being individually exposed to two oestrous Awassi ewe lambs for four 20-min periods. Bouts of leg kicking and anogenital sniffing were similar among breed groups. Mounting frequency was greater (p < 0.05) in RA than in A and CA ram lambs. Tail-raising was greater (p < 0.05) and mating rate tended to be greater (p < 0.10) in A than in RA and CA ram lambs. The number of mounts per tail-raising (efficiency) was influenced by breed group and test day (p < 0.05). Awassi ram lambs maintained the best efficiency throughout the experiment. Efficiency in RA and CA ram lambs improved with each test day. Results of the present study indicate that RA ram lambs have greater mounting frequency than A and CA, while Awassi are more capable of mating with fat-tailed females than the CA and RA ram lambs.     

Prolonged Duration of Fertility of Dog Ova

The fertile period for natural mating in dogs extends from before ovulation until day 5 post ovulation (PO) and involves a delay in oocyte maturation until 2–3 days PO and viability of secondary oocytes for 48–60 h or more. Spermatozoa do not enter the uterus after vaginal insemination in late oestrus. Cervical closure appears to occur on average 5 days PO, but conception may occur following intrauterine artificial insemination (IUAI) up to 8 days PO. Therefore, the present study was conducted to clarify the duration of fertility of canine ova. Using IUAI at 6, 7, 8 and 9 days PO (n = 5 bitches each) conception rates were 100%, 71.4%, 37.5% and 0%, respectively, with an average litter resorption rate of 30.8%, and with mean litter sizes and times to delivery PO being 4.3 ± 1.6 and 64.3 ± 0.3 days, 4.0 ± 1.4 and 66.3 ± 0.4 days, and 2.5 and 68 days for IUAI at 6, 7 and 8 days, respectively. The high pregnancy rates with IUAI at 6 and 7 days PO confirm that many canine oocytes are fertile at 4–5 days after maturation. The high rate of resorption was presumably because of aging of ova or asynchrony between embryonic development and the intrauterine environment.     

Response of fat-tailed Syrian Awassi ewes to accelerated lambing systems

Fifty cyclic fat-tailed Syrian Awassi ewes aged 2–4 years, with a mean weight of 51.4 kg, were used for 4 years to assess the accelerated lambing system (three lambings in 2 years). Ewes were divided into two groups: treated (T) and untreated (C). Ewes in the T group were treated with flugestone acetate for 14 days and injected intramuscularly at sponge withdrawal with 500 IU of equine chorionic gonadotropin (eCG). Results indicated that ewes in the T group exhibited oestrus and were mated within 5 days post sponge removal compared to 11 days for ewes in the C group, and the difference in oestrus response between the two groups was significant (P < 0.001). Repeated hormonal treatments had no significant (P > 0.05) effect on the lamb birth weight. However, significant (P < 0.001) differences in the lamb birth weight were observed between singles and multiple births. In the treated ewes, the total number of lambs born was 211–157 parturitions, and the multiple birth rate reached 27.4%, whereas the rate in the untreated group was 6.3% with the difference being significant (P < 0.05). In the untreated ewes, the total number of lambs born was 14–13 parturitions (12 singles and 1 twin). Fecundity rates were 135.1% and 106.3% in the treated and untreated ewes, respectively, and the difference was significant (P < 0.05). Repeated administration of eCG had no negative effect on fertility of Syrian Awassi ewes. However, anti-eCG antibodies were produced following eCG injections with extremely high individual differences in the immune response among ewes.     

The effects of time and dose of pregnant mare serum gonadotropin (PMSG) on reproductive efficiency in hair sheep ewes

The aim of this study was to evaluate the effects of dose and application time of pregnant mare serum gonadotropin (PMSG) on reproductive performance of hair sheep ewes synchronized with fluorogesterone acetate (FGA) under tropical conditions of Northeastern Mexico. Ninety-nine hair ewes (63 Blackbelly and 36 Pelibuey) were treated with intravaginal sponges during 10 days. After insertion of FGA sponges, ewes were divided into four groups, and PMSG was injected intramuscularly at doses of 100, 200, and 400 IU. Relative to FGA sponge removal, PMSG was administrated at −48 h, −24 h, and at sponge removal. PMSG was not administered to the control group. Control ewes had similar (P > 0.05) lambing rate, fertility, and fecundity than those treated with 100 IU of PMSG, but lower (P < 0.05) percentages to these variables than those treated with 200 and 400 IU of PMSG. Time to estrus decreased linearly, and ovulation rate increased quadratically as PMSG dose increased (0 to 400 IU). Administration of PMSG before sponge removal increased (P < 0.01) response to estrus and decreased (P < 0.01) interval to estrus compared with control. Ovulation rate, lambing rate, fertility, and fecundity were not affected (P > 0.05) by administration time of PMSG. Both dose and time of PMSG application did not affect (P > 0.05) pregnancy rate, percentage of single and multiple lambing, and prolificacy. In conclusion, results show that the dose of 400 IU of PMSG administered before sponge withdrawal in an estrus synchronization protocol improved reproductive efficiency of hair sheep ewes.     

Estrus synchronization in sheep with synthetic progestagens

Sixteen female sheep of Degua breed were assigned to receive either the full dose of norgestomet ear implant and injectable solution containing norgestomet and estradiol valerate (n = 8) or half the dose (n = 8). The ear implants were removed in both groups on day 12. All ewes received an intramuscular administration of 500 IU PMSG at implant withdrawal. Synchronized ewes were individually hand mated twice at 48 and 60 hours after implant removal. One ewe in each group however refused mating on both occasions. Pregnancy diagnosis was conducted by bimanual external palpation 90 to 100 days post mating. The conception rates (3/7, 42.85%) and (5/7, 71.42%) were recorded in the two treatment groups, respectively. All eight ewes lambed between 145 to 153 days post mating. In group I ewes carried only singletons (prolificity rate 1.0) whereas in group II two ewes delivered twins, producing 7 lambs with prolificity rate of 1.4 (N.S). From this preliminary investigation it appears that the lower dose of norgestomet ear implants offers better option for estrus synchronization accompanied by higher fertility.     

Inhibitory Effect of Selenium Supplementation on the Reproductive Performance in Synchronized Merino Sheep at Range Conditions in a Selenium-deficient Area

The effect of selenium (Se) supplementation on the reproductive performance of Merino ewes mated out of the normal breeding season was studied in a 2 (no Se supplementation vs Se supplementation) × 2 (ewes mated at natural oestrus vs synchronized oestrus) factorial design with 50 ewes per treatment combination. Synchronization of oestrus was achieved by intravaginal insertion of 40 mg cronolone sponges for 14 days and administration of 440 IU PMSG at sponge withdrawal. Se supplementation was by the addition to the concentrate with 0.5 mg/kg of Se in the form of selenomethionin, for the 3 months prior to the mating and during gestation. Ewes were kept under range conditions in south‐west Spain, and exposed to Merino rams at a female: male ratio of 4 : 1 from 2 days following sponge withdrawal, or the equivalent time, for 21 days. Se supplementation alone did not improve significantly ewe fertility or lamb birth weight, but there was a positive effect of synchronizing ewes mated out of the breeding season as more of these ewes lambed and produced more lambs than those not synchronized. However, a strong interaction was found between synchronization and Se supplementation, causing a deleterious effect on the reproductive performance of ewes. This negative effect, presumably related to high embrionary mortality caused by Se toxicity, should be taken into account for oestrus synchronizing in Se‐deficient areas. The supplementation with Se, for the prevention of nutritional myodystrophy degeneration in lambs, should be conducted in a fashion which does not generate high levels of Se in the ewes around the mating period.     

Awassi sheep reproduction and milk production: review

Awassi is the local breed of sheep in Jordan and is the most important breed in the semi-arid regions of the near east countries. Awassi ram and ewe lambs reach puberty at around 8 and 9 months of age, respectively. The breeding season of Awassi ewes starts as early as April and lasts through September. After puberty, Awassi rams are sexually active throughout the year. The normal estrous cycle in Awassi ewes is 15–20 days (average 17 days). Estrus ranges from 16–59 h (average 29 h) during the breeding season. The reproductive performance of unimproved Awassi sheep has been low while improved Awassi has the highest fertility and milk production and are the heaviest among all Awassi populations. The gestation length varies from 149 to 155 days (average 152 days). Hormones that are commonly used for induction and synchronization of estrus in Awassi ewes include progestins, gonadotropins and PGF2α. An Awassi ewe produces 40–60 and 70–80 kg of milk per 150-day lactation period under traditional and improved production systems, respectively, in addition to the suckled milk left for lambs until weaning. The improved Awassi has the highest milk production among all Awassi populations and may reach 506 L over 214-day lactation period. The objective of this review is to summarize the reproductive pattern and milk production of Awassi sheep in the Middle East region.     

The use of melatonin and progestagen–eCG to initiate reproductive activity in prepuberal Awassi ewe lambs

This experiment was conducted to evaluate the effect of administering hormonal treatments (melatonin and progestagen/equine chronic gonadotropin (eCG)) on advancing puberty in Awassi ewe lambs. Fifty-one 6-month-old ewe lambs of similar body weights (around 28 kg) were randomly assigned into four treatment groups; control (CON; n?=?14), melatonin (MEL; n?=?13), melatonin plus progestagen–eCG (MELPP; n?=?11), and progestagen–eCG (PP; n?=?13). Ewe lambs in the PP and MELPP groups were fitted with intravaginal progestagen sponges containing 60 mg medroxyprogesterone acetate for 14 days; 400 IU eCG were administered to each of these ewe lambs on the day of sponge removal. Ewe lambs in the MEL and MELPP groups received subcutaneous melatonin implants (Regulin®, 18 mg melatonin) 36 days before sponge insertion. Hormonal treatment had no effect on ewe lamb body weight change. Estrous behavior was greater (p?p?p?p?相似文献   

Effect of Exogenous GnRH at the Time of Artificial Insemination on Reproductive Performance of Awassi Ewes Synchronized with Progestagen–PMSG–PGF2α Combination

This study was carried out to investigate the efficacy of PGF_2α for oestrus synchronization (ES) in Awassi ewes to which were administered the progestagen–PMSG combination, and to evaluate the effect of the exogenous GnRH administration immediately after the artificial insemination (AI) on their pregnancy rate and lambing performance during the breeding season. The ewes (n = 33) were treated with an intravaginal sponge impregnated with 30 mg fluorogestane acetate for 12 days and were injected with 500 IU PMSG at the time of removal of the sponge. The ewes were then divided into three equal groups of 11 ewes each. One millilitre of physiological saline (0.9% NaCl; placebo) was administered to each ewe in Group 1 at the time of second AI. Approximately 4 μg GnRH (busereline) was injected to each ewe in Group 2 immediately after second AI. A total of 150 μg PGF_2α (cloprostenole) was injected at the time of sponge removal on day 12 and 4 μg GnRH immediately after the second AI was also treated to each ewe in Group 3. Intracervical AI with diluted fresh semen was performed twice at 12 and 24 h following the onset of oestrus. The injection‐oestrus onset and injection‐oestrus‐end interval in Group 3 was significantly (p < 0.001) shorter than both Groups 1 and 2. Although the pregnancy rates of Groups 2 and 3 (81.8%; 9/11) were numerically higher than of Group 1 (63.6%; 7/11), the difference among the groups was statistically insignificant. The multiple birth rate of Group 3 was found higher than Groups 1 and 2. However, the number of single lambs of Group 1 was also higher than Groups 2 and 3 (p < 0.05). Despite the litter sizes of Groups 2 (1.27; 14/11) and 3 (1.55; 17/11) being numerically higher than Group 1 (0.73; 8/11), the differences among all the groups were statistically insignificant. In conclusion, the administration of PGF_2α at the time of removal of the sponge shortens the injection oestrus‐onset and oestrus‐end interval in Awassi ewes treated with progestagen–PMSG. Additionally, exogenous GnRH treatment immediately after the AI increases the multiple birth rate of Awassi ewes synchronized with progestagen–PMSG–PGF_2α combination.     

Bitter vetch grains as a substitute for soybean meal for growing lambs

Thirty-six male Awassi lambs, born within 8-day period, were reared on their mother's milk until they were weaned at 65 days of age. After weaning, lambs were divided into 3 groups of 12, according to their live weight, and housed in individual pens and offered three isonitrogenous experimental diets. The experimental diets consisted of a 15 to 85 forage to concentrate ratio differing in the proportions of soybean meal (SBM) and bitter vetch (Vicia ervilia) grain. Soybean meal and bitter vetch grain were present in the experimental diets in the following proportions: 14:0% (S), 7:8.4% (SV) and 0:15% (V), all on dry matter basis. The experiment lasted for 80 days in which lambs had ad libitum access to feed. Organic matter (OM), crude protein (CP) and neutral detergent fiber (NDF) intakes were all unaffected (P > 0.05) by the dietary treatment and averaged 875, 152 and 226 g/day, respectively. However, intake of rumen undegradable protein was decreased in the SV and V diets as compared to the S diet. Dry matter, OM, CP, NDF and energy digestibilities were all unaffected (P > 0.05) by the dietary treatment. Average daily gain (ADG) of all lambs was not affected by the dietary treatment and averaged 196 g/day. Feed to gain ratio was also unaffected by the treatment and averaged 5.3. However, feed cost/kg body weight change was reduced by more than 9% with the substitution of SBM with bitter vetch grain. In conclusion, partial or complete substitution of SBM with bitter vetch grain did not affect nutrient intake or growth performance of Awassi lambs and resulted in a decrease in feed cost.     

Qualitative and quantitative changes in the hypothalamus and the ependyma of the 3d cerebral ventricle in sheep after irradiation and hormonal stimulation

In the submitted work we concentrated our attention on the study of the changes in neurosecretion. PAS positive mucopolysaccharides in the hypothalamus and ependyma of the IIIrd cerebral ventricle and on studying the changes in the volume of the cell nuclei of the neurons of nucl. supraopticus (NSO), nucl. hypothalamicus centromedialis (NVM) and nucl. tuberomamillaris (NTM) of sheep after irradiation and after hormonal stimulation. We made our observations on 28 sheep of the Slovak Merino breed, of average live weight 35 to 40 kg, two- and three-years old in the period of physiological anoestrum. The first group of four ewes and the second group of four yearling lambs were controls. The third group of six ewes and the fourth group of six yearlings were exposed to irradiation all over with a dosage of 2.46 Gy (250 R) for a period of five days. To synchronize the oestrum of all the sheep we used agelline sponges which we fitted five days before irradiation. After the irradiation and removal of the sponges we gave the test sheep hormonal stimulation with 3 X 500 i. u. of serum gonadotropin. The fifth group of four ewes and the sixth group of four yearlings were only stimulated without irradiation. The fifth day after stimulation we slaughtered the sheep. We processed the brain samples by the usual histological methods. We carried out karyometric analysis with 3000X magnification and the measurement of 200 cells from one sample. We processed the values obtained mathematically according to Fischer and Inke (1956). We evaluated the quantity of neurosecretion material with a light microscope according to Nakahara (1962). We found that the multiplication of neurosecretion and the increased activity of the PAS reaction in the hypothalamic nuclei studied show that the irradiation and hormonal treatment stimulate the function of the hypothalamic structures. The results of the karyometric analysis in the yearlings also confirm this opinion. In the ewes the inhibitive influence of irradiation was probably manifest. The giving of hormones in combination with irradiation causes the multiplication of ependyma cells and the desquamation of surface layers.     

Experience from a 3-year administration of megestrol acetate of karakul sheep

Five milligram of megestrol acetate were orally used over ten days during mating periods to synchronise oestrus in caracool sheep. Eighteen days were allowed to elapse from the last administration of progestagen before 1,000 I.U. PMSG were injected to boost fertility. The test reported in this paper had been applied to a large sheep herd over three years. The following conclusions were drawn: Synchronised occurrence of heat in the mating period was not reduced by oral administration of 5 mg megestrol acetate over ten days for a period of three years (87.1 to 95.5 per cent). The fertilisation rate in response to first insemination was between 68.8 and 73.1 per cent. Birth to lambs was given by 85-92 per cent of the ewes after two inseminations. No fertility occurred in 1.5-3.1 per cent of all animals.     

Field Trial on Progesterone Cycles, Metabolic Profiles, Body Condition Score and their Relation to Fertility in Estonian Holstein Dairy Cows

Resumption of luteal activity postpartum and fertility were investigated in an Estonian Holstein high milk production and good fertility dairy herd. Body condition was scored after every 10 days in 54 multiparous dairy cows (71 lactations) calving inside from December to March during 4-year period. Blood samples were taken 1–14 days before calving and 1–14, 28–42 and 63–77 days after calving: analytes estimated were serum aspartate aminotransferase (AST), glucose, ketone bodies, total cholesterol, non-esterified fatty acids and triglycerides. The general linear mixed model was used to compare the data for cows with different characteristics in luteal activity postpartum based on their milk progesterone profiles. Forty-five per cent of cases had abnormal profiles; delayed resumption of ovarian cyclicity postpartum (DC) was the most prevalent abnormality. There was no difference in body condition scores between the groups. The DC and prolonged luteal phase groups had higher serum AST activity (p < 0.01) 1–14 days postpartum compared with normal group. The DC group also had higher cholesterol and triglyceride values (p < 0.05) 28–42 days postpartum and higher milk fat/protein ratio (p < 0.01) on the first month of lactation compared with normal profile group. Despite long post-calving anoestrous period (71 ± 5.0 days; mean ± SEM) DC group had 64.7% first service pregnancy rate (normal group 48.6% and PLP group 37.5%). This study did not find any detrimental effect of prolonged anovulatory period postpartum on subsequent fertility.     

Effect of Progesterone Prior to GnRH-PGF2α Treatment on Induction of Oestrus and Pregnancy in Anoestrous Awassi Ewes

An experiment was conducted to examine the effect of progesterone prior to a GnRH‐PGF_2α treatment on oestrus and pregnancy in seasonally anoestrous Awassi ewes. Twenty‐four ewes were randomly assigned to three groups to be pre‐treated with 60 mg medroxyprogesterone acetate sponges (group A), 600 mg progesterone sponges (group B) or blank sponges (group C) for 4 days. All ewes were injected with 100 μg of GnRH 24 h after sponge removal followed, 5 days later, by 20 mg PGF_2α injection. Ewes were exposed to three fertile rams at the time of PGF_2α injection (day 0, 0 h) and were checked for breeding marks at 6‐h intervals for 5 days. Blood samples were collected from all ewes 1 day (day ?10) prior to sponge insertion, at the time of sponge removal (day ?6), 1 day following sponge removal (day ?5, at the time of GnRH injection) and at the time of PGF_2α injection (day 0) for analysis of progesterone. Progesterone concentrations on days ?10 and ?5 were basal and averaged 0.2 ± 0.04 and 0.2 ± 0.2 ng/ml, respectively. Progesterone concentrations on day ?6 were elevated only in group B ewes and were higher (p < 0.0001) than those of groups A and C. Progesterone concentrations on day 0 were higher (p = 0.002) in groups A and B than group C. Oestrous responses occurred only in ewes of groups A and B (p > 0.05). Induced oestrus conception rate was greater (p < 0.01) in group A than groups B and C. Ewes returned to oestrus 17–20 days following day 0 were two of eight, six of eight and three of eight of groups A, B and C, respectively, all of which eventually lambed. The overall lambing rate was 82% in progesterone‐primed ewes compared with only 38% non‐progesterone‐primed ewes (p < 0.05). Progesterone priming apparently sensitizes GnRH‐PGF_2α‐treated seasonally anoestrous ewes and increases their response in oestrus and pregnancy rates.     

The effect of active immunization of ewes against androstenedione on lambing rate and production

Active immunization of sheep of the Dala breed against androstenedione caused a mean increase in number of lambs born (live-born and stillborn) of 0.29 (p less than 0.01). In yearlings the difference was 0.43 lambs (p less than 0.01) and in older ewes 0.23 lambs (p less than 0.1). Five of the older immunized ewes gave birth to quadruplets while none in the control group gave birth to more than 3 lambs. In older ewes there was an increase in the number of stillborn lambs. In young immunized ewes the mean ewe production, registered as total live weight of lambs in the autumn, was 11.3 kg higher than in control animals. This difference was however not significant (p less than 0.1).