Effect of feeding calcium salts on performance of nursing Awassi ewes

Twenty nursing Awassi ewes (BW = 50 ± 2.35 kg, age = 4.5 ± 1.2 years) with their lambs were used to evaluate the effects of feeding calcium salts in lactation diets on performance and pre-weaning growth of their lambs. Treatments were 0% calcium salts (CON) or 5% calcium salts (FAT). At the end of the study, a digestibility experiment was performed. Milk yield was greater (P < 0.05) for ewes fed the FAT diet than the CON diet. Milk composition was similar (P > 0.05) between diets. However, milk energy value (kcal/day) tended to be greater (P = 0.07) for the FAT diet than the CON diet. Concentrations of milk C18:1c9 and C20:0 were greater (P < 0.05) in ewes fed the FAT diet than the CON diet. However, concentration of trans-10, cis-12 CLA was lower (P = 0.05) in the FAT diet than in the CON diet. No differences in feed intake and body weight change were detected between diets. Digestibility of dry matter, organic matter, crude protein, ether extract, neutral detergent fiber, and acid detergent fiber were similar (P > 0.05) for diets. For lambs, weaning weight was not affected by treatments. However, average daily gain and total gain were greater (P = 0.053) for the FAT diet than the CON diet. Results suggest that supplementing lactating ewes with calcium salts at the beginning of lactation phase improves daily milk yield of ewes and pre-weaning growth of their lambs with no major negative impact on feed intake and digestibility.     

Effect of season and lactation on postpartum fertility of Polypay, Dorset, St. Croix and Targhee ewes

The objective of this study was to compare rebreeding activities of spring- vs fall-lambing Polypay, Dorset, St. Croix and Targhee ewes that either suckled their lambs for 40 d or had lambs weaned at birth. Seasonal effects of male fertility were reduced by utilizing an excess number of fertile rams in the spring. Plasma concentrations of progesterone were monitored to assess days to the first normal ovulation, days to conception and estrous vs anestrous activity. Breed, season and lactation affected the rebreeding performance. Dorset ewes had similar conception rates between spring and fall but a shorter interval from lambing to first ovulation in the fall. Polypay and Targhee ewes were the opposite; they had higher conception rates in fall than in spring matings with no seasonal influence on postpartum interval. Postpartum ewes in the fall had higher conception rates, and fewer of these ewes became anestrous or had estrous cycles of abnormal duration than of those ewes lambing in the spring. Ewes that suckled for 40 d in the spring had delayed estrous activity, but when these ewes became estrual they had higher conception rates than ewes whose lambs were weaned at birth. Lactation had no inhibitory affect on the postpartum interval of fall lambing ewes. These data suggest that the response of different breeds to various components of postpartum fertility varies with season and management of the flock.     

Naloxone-reversible inhibition of luteinizing hormone in postpartum ewes: effects of suckling and season

Involvement of endogenous opioids in inhibition of luteinizing hormone (LH) release and stimulation of prolactin (PRL) release was investigated by injecting the opioid antagonist naloxone into 18 ewes on d 7 and 8, d 12 and 13, and d 18 and 19 postpartum. Compared with control injections of saline, iv naloxone (1 mg/kg) increased serum concentrations of LH and decreased serum PRL in samples collected 15, 30 and 45 min after each injection. Ewes lambing in the spring (March) or autumn (September and October) that nursed one or two lambs did not differ in their LH and PRL responses to naloxone. Autumn-lambing ewes from which lambs were weaned within 1 d after parturition did not differ from ewes of the autumn-nursed group in any of the following characteristics: 1) serum LH increases following naloxone, 2) basal secretion of LH, 3) postpartum interval to first increase in serum progesterone and 4) relative decrease in serum PRL after naloxone despite large differences in basal PRL secretion. In summary, postpartum expression of a naloxone-reversible inhibition of LH release and stimulation of PRL secretion did not depend on suckling stimuli or differ between autumn and spring parturitions.     

A study on superovulation using FSH and eCG in Awassi ewes

The present study was conducted to evaluate superovulatory treatments in Awassi ewes by eCG and FSH. High number of unovulated follicles (P < 0.05) was observed in ewes treated with eCG in non-breeding season. It could be concluded that using FSH to induce superovulation in Awassi ewes is better than eCG.     

Physiological responses to water restriction in dry and lactating Awassi ewes

The effect of water restriction in Awassi ewes was assessed under two physiological conditions: lactating and dry, over a 3-week-period (August–September, 2002). Eight dry and eight lactating Awassi ewes (with their lambs) were assigned to one of two watering regimes: watered once every three days and daily watering, respectively. Weather data, body weight and rectal temperature were recorded. Venous blood was sampled on the watering day of the water-restricted group, and subjected to haematological, biochemical and electrolytes analysis. Ewes under water restriction lost more weight and had higher packed cell volume, haemoglobin, serum cholesterol, urea, creatinine, total protein and albumin as compared to daily-watered animals. However, lactation seemed to have no significant effect on these serum components. As for blood pH and electrolytes, Na⁺ and Cl⁻ were significantly higher under water restriction; whereas significantly lower K⁺ and Ca⁺⁺ but higher pH and Cl⁻ were observed in lactating animals. Finally, lower cortisol concentrations were observed in water-restricted animals, warranting further studies on the hormonal adaptation to long term water stress. It was concluded that water restriction induces similar changes in blood physiological indicators in dry and lactating Awassi ewes; while lactation beyond the first month post partum seems to mostly affect blood electrolytes.     

Increased ovulation rate of adult ewes treated with anti-bovine LH antiserum during the normal breeding season

Adult Suffolk ewes (n = 14) were treated on d 10 of the estrous cycle with anti-bovine luteinizing hormone (LH) antiserum. Control ewes (n = 10) were treated with normal horse serum. Estrous behavior and the number of corpora lutea and ovarian follicles were examined at the subsequent estrous cycle. Daily plasma concentrations of progesterone (P4), follicle stimulating hormone (FSH) and estradiol were determined before and after treatment. Ewes treated with antiserum had a higher (P less than .05) ovulation rate (2.7 +/- .2) than did controls (2.1 +/- .1). No differences were found in the numbers of large (greater than 5 mm) or small (less than 5 mm) follicles between treatment groups. Estrus was delayed (P less than .025) approximately .6 d/in ewes treated with antisera. Immunoreactive FSH increased (P less than .05) within 1 d after treatment and remained higher than the controls for 5 d. Peak estradiol concentrations occurred on d 17 for treated ewes compared with peak concentrations on d 15 or 16 for control ewes. The P4 concentrations were generally less (P less than .025) in treated ewes throughout the luteal phase of the treatment cycle. These data demonstrate that ovulation rate is increased in ewes treated with LH antiserum. The marked increase in plasma FSH suggests a possible mechanism whereby ovulation rate is enhanced.     

Reproductive response in suckling Corriedale ewes to the ram effect during the non-breeding season: Effect of postpartum condition and the use of medroxyprogesterone priming

The response to the ram effect and the use of progestagen priming was studied in postpartum suckling Corriedale ewes. Two experiments were carried out during the non-breeding season. In experiment 1, the effectiveness of the ram effect to induce fertile oestrus in postpartum ewes was determined. While no significant differences in the frequency of ewes in oestrus were found, the overall conception rate was significantly higher in ewes that were weaned at least 6 months before the study started (63.3%) than in 60–90 days postpartum ewes (45.3%, p < 0.01). In experiment 2, the influence of medroxyprogesterone acetate priming on the response to the ram effect in suckling Corriedale ewes was determined. The frequency of ewes in oestrus and conception rate between ewes that remained unprimed and 6-days-primed ewes were similar. We conclude that it is possible to induce oestrus in postpartum suckling Corriedale ewes using the ram effect during the non-breeding season and that the use of progestagen priming seems to be ineffective in improving the response of postpartum ewes to the ram effect.     

Determinants of attenuated LH-release associated with the first ovulation of the equine breeding season

An attenuated ovulatory rise in circulating concentrations of LH is characteristically associated with the first seasonal reproductive cycle of horse mares. Unlike ovulations (OV) of subsequent estrous cycles, the first OV of the breeding season (OV1) is not preceded by elevated concentrations of progesterone (PROG). Hence, the ability of pretreatment with PROG to abolish attenuation of LH-secretion associated with OV1 was investigated. Ten nonpregnant anestrous mares were randomly divided into 2 groups; control (C) and treated (T). Per individual, when diameter of the largest follicle was consistently greater than or equal to 35 mm, C mares received 3 times daily injections of cottonseed oil (IM), for 15 d or until OV, while T mares received exogenous PROG (IM) for 15 d, in a manner designed to mimic a diestrous pattern of release. Jugular blood samples were collected daily from onset of treatment through 10 d following the third OV (OV3). Repeated measures analyses of area under the ovulatory LH-rise (AUC) and the maximum concentration of LH associated with OV (MAX) revealed a significant main effect of OV (P less than .005) but no main effect of group or OV by group interaction (P greater than or equal to .5). When groups were combined, a significant increase in mean AUC and MAX from OV1 to OV3 was observed (P less than .01). To evaluate the influence of hypothalamic-hypophyseal recrudescence on ovulatory LH-release at OV1, 16 mares were bred to foal, and subsequently initiate reproductive activity, early (E; mid April; n = 8) or late (L; mid July; n = 8) in the year. A significant OV (1, 2 or 3) by group (E or L) interaction was observed for AUC (P less than .06) and MAX (P less than .04). Mean AUC and MAX increased progressively from OV1 to OV3 in E mares (P less than .05). In L mares, neither AUC or MAX changed from OV1 to OV3 (P greater than .4). Based on these data, we suggest that attenuation of the LH-rise at OV1 in the mare, is a consequence of incomplete recrudescence of the hypothalamic-pituitary axis.     

A comparative study of induction of estrus and ovulation by three different intravaginal devices in ewes during the non-breeding season

The aim of the present study was to compare three methods of estrus synchronization in ewes during the non-breeding season. Forty-two ewes were randomly grouped for three treatments with different intravaginal devices for 12 days: Group A) CIDR, Group B) Self-made P sponge, Group C) MAP (medroxyprogesterone acetate) cream sponge. Furthermore, all groups were divided into two treatments with (R) or without ram presence to examine the "ram effect". Blood was collected from all treated ewes, and progesterone (P(4)), estradiol 17-beta (E(2)) and luteinizing hormone (LH) concentrations were measured by enzyme-immunoassay. All ewes showed estrus behavior between Day 0 to 3 after device removal, and the mean onset times of their estrus were 23.0, 33.0 and 21.0 h for Groups AR, BR and CR, respectively. On Day 5 as examined by laparoscopy, the ovulation rates (and number of ovulated ewes) were 1.45 (11/11), 1.25 (12/14) and 1.21 (14/14) for Groups A, B and C, respectively. In Group C, the time to LH surge was significantly (P<0.05) later (32.4 h) than those in Groups A (27.0 h) and B (25.5 h). Ram presence did not affect the number of ovulated ewes, ovulation rate or time to LH surge. The ram introduction group had significantly (P<0.05) lower E(2) concentrations during the period from 0 h to 36 h than the groups without ram presence. These results suggest that the self-made P sponge or MAP cream sponge was effective as well as CIDR, and ram introduction was not necessary, for induction of estrus and ovulation during the non-breeding season.     

Use of dried poultry litter in the diet of pregnant and lactating Awassi ewes

Summary Two groups of 45 Awassi ewes, were fed a control diet (group C) or a diet containing 0.30 poultry litter from laying birds (group PL). The experiment began when the rams were put with the ewes and continued through pregnancy and lactation. Mean weight changes of ewes of both groups were small and not significantly different. The numbers of ewes that lambed and the numbers of lambs weaned, as proportions of the number of ewes mated, were 0·91 and 0·73 respectively for group C, and 0·93 and 0·70 for group PL. The mean weaning weight of lambs of group C (20·6 kg) was just significantly greater than the value for group PL (18·4 kg) but the estimated mean daily milk yields, 0·716 and 0·626 kg respectively, did not differ significantly. Differences in breeding and lactation performance, between ewes given the control and those given the poultry litter diet, were small for all the data obtained. Also, there was no disease problem related to the use of poultry litter; and the food products milk and cheese, from ewes given poultry litter, were just as acceptable as those from ewes given the control diet.

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Uso De Cama De Ponedoras En La Dieta De Ovejas Prenadas Y En Lactacion De La Raza Awassi

Resumen Dos grupos de 45 ovejas Awassi, recibieron una dieta control (grupo C), o una dieta con 0·30 de cama de ponedoras (grupo PL). El experimento comenzó cuando los carneros fueron puestos con las hembras y continuó durante la preñez y lactación. Los cambios medios de peso de las ovejas en ambos grupos fueron pequeños y no significativamente diferentes. El número de ovejas que parieron y el número de corderos destetados, como proporción del número de ovejas apareadas, fueron 0·91 y 0·73 respectivamente para el grupo C, y 0·93 y 0·70 para el grupo PL. La media del peso de los corderos al destete pertenecientes al grupo C (20·6 kg) fue significativamente más alto que el valor obtenido para el grupo PL (18·4), pero la media estimada del producido diario de leche de los dos grupos 0·716 y 0·626 kg respectivamente, no difirieron significativamente. No hubo diferencias reproductivas, ni de lactación entre los dos grupos. Tampoco se detectaron enfermedades relacionadas con el suministro de cama de ponedoras. Los productos y subproductos lech y queso, no fueron afectados por la alimentación experimental.

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Emploi De La Litere De Volaille Dans La Ration Des Brebis Awassi Gestantes Et Allaitantes

Résumé Deux groupes de 45 brebis Awassi ont reçu un régime témoin (groupe C) et un régime contenant 0,30 de résidu de litière sèche de pondeuses (groupe PL). L'expérience a débuté au moment où les béliers sont introduits parmi les femelles et s'est poursuvie pendant la gestation et l'allaitement. Les variations du poids moyen des brebis des deux groupes ont été faibles et les différences statistiquement non significatives. Le nombre d'agnelages et celui des agneaux sevrés, en tant que proportion par rapport au nombre de brebis accouplées, a été de 0,91 et 0,73, respectivement pour le groupe C, et de 0,93 et 0,70 pour le groupe PL. Le poids moyen au sevrage des agneaux du groupe C (20,6 kg) a été à peine plus élevé que le même facteur pour le groupe PL (18,4 kg), mais le rendement moyen quotidien estimé en lait: 0,716 et 0,626 kg respectivement, n'étaient pas significativement différent. Les différences dans les performances de gestation et de lactation entre les brebis nourries avec la ration témoin (C) et celles recevant le régime avec la litère de volaille séchée (PL) ont été faibles pour toutes les données obtenues. Enfin, il n'y aeu aucun problème sanitaire quant à l'emploi de la litère sèche et les produits alimentaires, lait et fromage de ces animaux étaient aussi acceptables que ceux des témoins

     

Energy balance, first ovulation and the effects of naloxone on LH secretion in early postpartum dairy cows

Relationship among energy balance (EB), first ovulation, circulating metabolites and opioid involvement in peripheral LH concentrations were assessed in 40 multiparous Holstein cows assigned randomly to an experiment with a 2 x 2 factorial arrangement of treatments. Cows were either milked normally (2x/d) and expected to be in negative EB (LAC) or were milked for only 1 d postpartum (PP) to ensure a rapid return to positive EB (NONLAC). Blood samples were collected from NONLAC cows every 12 min for 16 h on d 7, 10, and 14 PP and from LAC cows on d 7, 14, 21 and 28 PP. Within each group, half the cows received naloxone (50 mg/h) and half received saline during h 9 to 16 of each frequent sampling series. The mean number of LH pulses/8 h for NONLAC cows was 4.3, 4.7 and 5.3 at 7, 10 and 14 d PP and for LAC cows 4.3, 5.7, 6.4 and 7.0 at 7, 14, 21 and 28 d PP, respectively. The LH pulse frequency was not different between NONLAC and LAC cows at 7 and 14 d PP, yet NONLAC cows had fewer days to first ovulation (P less than .01). Naloxone did not affect any parameters of LH secretion in either group. Following parturition, NONLAC cows averaged 4.0 d to negative EB nadir and 14.3 d to first ovulation. The LAC cows averaged 13.6 d to negative EB nadir and 27.0 d to first ovulation. Days PP to first ovulation were highly correlated (r = .85) with days PP to negative EB nadir.(ABSTRACT TRUNCATED AT 250 WORDS)     

小尾寒羊复旧期子宫组织内胶原纤维的研究

从细胞、亚细胞水平来揭示羊子宫复旧过程中的组织学变化规律。用透射电子显微镜(TEM)对9只产程正常、健康的小尾寒羊子宫复旧期间子宫结缔组织内胶原纤维的变化进行了研究。试验结果表明:在产后1~7d,胶原纤维排列不规则,胶原呈片段存在,其内部溶解形成形态各异的空腔;从分娩第13天开始,胶原片段数量减少,排列较规则;到产后第25天时,胶原纤维束纵横交错排列,横纹清楚,无胶原片段。     

Effect of supplements during the cold season on the reproductive system in prepubertal Tibetan sheep ewes

We examined the development of the reproductive system in prepubertal Tibetan sheep ewes when fed only oat hay (CON) or supplemented with either lick blocks (BS) or concentrate feed (CS) during the cold season. The average daily gain of the CS ewes was greater than that of the BS ewes (P  < 0.05), which was greater than that of the CON ewes. The same pattern was observed in the number of ovarian follicles (P  < 0.001), that is, CS > BS > CON. Serum concentrations of gonadotropin‐releasing hormone, follicle‐stimulating hormone, luteotrophic hormone, estradiol and progesterone in the CS and BS groups were higher than in the CON group (P  < 0.05). The messenger RNA (mRNA) expression of KiSS‐1, GPR54 (G protein‐coupled receptor 54), ERα (estradiol receptor α) in the hypothalamic anteroventral periventricular area of the CS group were higher than in both the BS and CON groups (P  < 0.05), while the BS group was higher than in the CON group (P  < 0.05). Similar differences among groups were observed for gonadotropin‐releasing hormone receptor mRNA expression in the pituitary, follicle‐stimulating hormone receptor and luteinizing hormone receptor mRNA expression in the ovary. These results indicated that the KiSS1/GPR54 system was more active with nutrition or trace mineral supplementation during the cold season. The system stimulated the hypothalamic–pituitary?gonadal axis and enhanced folliclar development in prepubertal Tibetan sheep ewes. We concluded that energy, protein and trace minerals supplements could improve the reproductive performance of Tibetan sheep on the Qinghai‐Tibetan plateau.     

Distribution of time to first postpartum estrus in beef cattle

The function of a distribution that describes postpartum interval (PPI) under any experimental treatment is useful for simulation modeling, understanding the effects of stimuli on the endocrine system, and estimating the average PPI in experiments terminated before all animals have expressed estrus. This study was undertaken to compare the fit of three statistical distributions, the Weibull, the log-normal, and the linear hazard rate (LHR), to the empirical distribution of PPI for five treatment regimens: no bull exposure postpartum, bull exposure from 53 d postpartum, bull exposure from 3 d postpartum, and bull exposure from an average of 63 d postpartum for 2-yr-old cows and for mature cows. The Weibull and the log-normal distributions deviated considerably from the empirical distribution. The LHR distribution with parameters changing over three different regions gave an excellent fit. The resulting hazard rate (instantaneous probability of a cow expressing her first estrus at time t postpartum) revealed a low probability of expressing estrus within 27 d postpartum (43 d for 2-yr-olds). For cows not exposed to bulls, the hazard rate increased slowly with time. For cows exposed to bulls after 3 d postpartum, the hazard rate increased rapidly between d 27 and d 50. For cows exposed to bulls after 53 d postpartum, the hazard rate increased instantaneously approximately 12 d after initial exposure to bulls. This increase was also seen when cows were exposed to bulls beginning at a constant date (at an average of 63 d postpartum). Because of lack of fit, the Weibull and the log-normal distributions should not be used in survival analysis of PPI.(ABSTRACT TRUNCATED AT 250 WORDS)     

Human chorionic gonadotropin (hCG): the effect of dose on ovulation and pregnancy rate in Thoroughbred mares experiencing their first ovulation of the breeding season

AIM: To determine the effect of hCG dose on ovulation and pregnancy rate in Thoroughbred mares experiencing their first ovulation of the breeding season. METHODS: Over 3 successive breeding seasons, a total of 101 mares were randomly assigned to 1 of 4 treatment groups (intravenous injection of either saline, 1500, 3000, or 6000 IU hCG), as they approached their first ovulation of the breeding season. Mares were bred 1 day post-injection to 1 of 11 stallions, and every other day until ovulation occurred. Data were analysed using multivariable logistic regression with correction for over-dispersion due to clustering. RESULTS: Mares treated with hCG were more likely to ovulate within 72 h of treatment than mares treated with saline (p<0.001); there was no significant difference between doses of hCG on risk of ovulation (p>0.15). Farm also had a significant impact on the risk of ovulation (p=0.027). Mares treated with hCG were more likely to be diagnosed pregnant 14 days post ovulation than saline-treated mares (p=0.081, p=0.029 and p=0.026 for the 1500, 3000 and 6000 IU doses, respectively); there was no significant difference between doses of hCG on risk of pregnancy (p>0.45). CONCLUSIONS: A single injection of hCG (1500-6000 IU) is effective at inducing ovulation in late transitional mares and increases the likelihood of pregnancy at 14 days post ovulation. This paper supports the use of hCG as an integral part of optimal broodmare management.