Reproductive Traits and the Physiological Background of the Seasonal Variations in Egyptian Suffolk Ewes under the Conditions of Egypt

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1 Annals of Arid Zone 43(2): , 2004 Reproductive Traits and the Physiological Background of the Seasonal Variations in Egyptian Suffolk Ewes under the Conditions of Egypt I.F.M. Maral, A.A. EI-Darawany, E.I. Abou-Fandoud and M.A.M. Abdel-Hafez I Department of Animal Production, Faculty of Agricult~re, Zagazig University, Zagazig, Egypt 2 Department of Sheep and Goats, Institute of Animal Research, Ministry of Agriculture, Dokki, Egypt Abstract: The calculated temperature-humidity index indicated absence of heat stress during winter and exposure to very severe heat stress during summer and to severe heat stress during autumn, under the sub-tropical conditions of Egypt. Cervical mucus ph was lower significantly (P<O.O1), while viscosity (spinnbarkiet) and electric resistance (ER) were higher significantly (P<O.O1) in winter than in summer and autumn breeding seasons. Ferning arborization was not affected by season of the year. Glucose, inorganic phosphorus and zinc were higher significantly (P<O.05) in cervical mucus in winter and autumn than in summer breeding season. The progesterone hormone level in urine (efficacious) in ewes at day 21 after mating was higher significantly (P<O.05) in summer than in winter and autumn seasons. Conception rate was higher significantly (P<O.05) in ewes mated in winter and autumn than in those mated in summer breeding season. Key words: Egyptian Suffolk ewes, reproductive traits, breeding season, heat stress. physiological status. One of the early trials which was carried out to improve the Ossimi local sheep, was by grading up to 16 UK Suffolk sheep, in Ministry of Agriculture. The crossbreeding program began in the year 1957, where inter se mating was carried out. The obtained flock (Egyptian Suffolk) was of 70 to 90% Suffolk blood (Aboul-Naga and Aboul-Ela, 1985). The common breeding season in the country is during May-June. Lambing and growth of lambs occur during the milder' weather during beginning of October. This also coincides with the availability of Egyptian clover, the main fodder crop in the country. However, the climate during the breeding season is hot that adversely affects the animal's productive and reproductive abilities (Daader et al., ]985; Kamal et al., 1988; Habeeb et al., 1992; Marai et al., 1996). The objectives of the present investigation were to study the effects of stressful hot summer conditions in Egypt on reproduction of Egyptian Suffolk female sheep. Materials and Methods The present study was conducted in the Department of Animal Production, Faculty of Agriculture, Zagazig University, Zagazig, Egypt. The experimental work was carried out at EI-Gemmaiza Experimental Station located in mid-nile Delta (30.5 N) and the laboratory work was conducted in the Department of Sheep and Goat Research.

2 178 MARAI et at. both belonging to Animal Production Research Institute, Ministry of Agriculture, Egypt. A total number of 215 ewes of Egyptian Suffolk sheep was used, under 3 lambings!2 years system (December-February as winter season, May-July as summer season and August-October as autumn season). The ewes were of 1.5 to 4.0 years of age and 45 to 60 kg body weight. The number of ewes during the different seasons were 71 in winter, 68 in summer and 76 in autumn. The animals were healthy and clinically free from external and internal parasites. Ewes were housed in semi-open sheds during the experimental periods. The partitions were 4 x 12 m. Each shed pen was surrounded by 2 m high brick walls. Animals were offered their feed requirements according to NRC (1985). The animals were watered at 9.00, 12.00, and h in summer and at 9.00, and h in winter. Additional ration for rams were offered 15 days before and after beginning of the breeding season (total 35 days). Flushing of ewes was done by feeding 1.0 kg concentrate and rice straw ad lib. The concentrates and roughages (Table I) were analyzed following AOAC ( 1980). Cervical mucus traits Ewe cervical mucus samples were collected by plastic pipette during oestrus (heat). Smear was immediately prepared using a drop of fresh mucus, and was examined under microscope after drying. For ferning arborizaion, ferning pattern in cervical mucus was classified into fine ferning (4 degrees), intermediate (3), clump (2) and no fern (I), based on the apparent thickness and arrangement of the fern branches according to EI-Darawany and EI-Sayaid (I 994). Electrical resistance (ER) of cervical mucus was measured by avometer (Model H-M 101). The ph was measured by ph paper. Spinn-barkiet (viscosity) of cervical mucus was tested simply between fingers. Cervical mucus samples were collected and stored at -10 C until analyzed chemically. At the end of the pregnancy period, conception was calculated. Lambing rate was calculated as follows: Lambing rate (%) Number of offspring born (alive or dead) / Number of ewes lambed (A live or dead offspring) x 100 Urine samples from ewes were collected before, during oestrus and 2] days after mating and stored at -10 C until analyzed Table J. Chemical analyses of the diets used in experimental trials Item Om CP CF EE NFE OM Ash Sel. Car. (%) (%) (%) (%) (%) (%) (%) (%) (%) Concentrates Barley Rice straw Sel. = Selenium and Car.= Carotene.

3 EGYPTIAN SUFFOLK EWES 179 for progesterone level. For estimating efficacious progesterone in fresh urine, a drop of 5% potassium permanganate was mixed with I ml fresh urine for conversion of pregnandiol to progesterone by oxidation to the hydroxyl group according to EI-Darawany (1992). Glucose in plasma was measured by glucose oxidase method of Huggett and Nixon (1957). Inorganic phosphorus in serum was measured according to Fiske and Subbarow (1925), and zinc by. using atomic absorption spectrophotometer according to Whiteside ( 1979). Progesterone hormone (P4) in urine was assayed using anti-pro~esterone antibody-coated tubes and labelled progesterone kit manufactured by Immunotech A Coulter Company, Marseille Cedax 9, France, according to Haynes et al. (1980). Temperature-humidity index Ambient air temperature, floor temperature and relative humidity (RH) were recorded during physiological and scrotal measurements and semen collection. Ambient air and floor temperatures were recorded using Mercury thermometer to the nearest O.loC. Maximum and minimum temperatures. were recorded using thermometer. RH was recorded using hairhygrometer to the nearest I%. The average ambient temperature and RH were 14.5 and 79.5%, 28.2 and 61.4% and 25.9 and 65.6% in winter, summer and autumn seasons, respectively. Temperature-humidity index (THI) was estimated according to the following equation (Marai et al., 2000): THI = dboc - {( RH) (dboc )} The THI were classified as follows: <22.2 = no heat stress, <23.3 = moderate heat stress, <25.6 = severe. heat stress, and >25.6 = very severe heat stress. The calculated THI values were-14.5 in winter, 25.6 in summer and 24.7 in autumn. Statistical analysis The model used to study effects of season on cervical mucus traits, efficacious and non efficacious progesterone in blood and urine, conception and lambing rates in ewes, was as follows: Yij = 11 + Si + eij where, f.l = overall mean, Si = fixed effect of i th season (i = I, 2 and 3) and eij = residual. The statistical analysis was computed using analysis of variance procedure. Significant differences between means were separated by Duncan's Multiple Range test procedure described in SAS (1995). Results and Discussion Temperature-humidity index The calculated THI values were 14.5 (daylight length h) during winter, 25.6 (day light length h) during autumn and 33.3 during summer (with daylight length 14.05), indicating absence of heat stress during winter, exposure of the animals to very severe heat stress during summer and to severe heat stress in autumn. Cervical mucus traits The cervical mucus ph and electric resistance (ER) were significantly lower

4 180 MARAI et al. Table 2. Least square means (±S.E) of cervical mucus traits in Egyptian Suffolk ewes as affected by breeding season Variables Winter Breeding Summer seasons Autumn Significance P<O.O I. NS * ** ** * P<O.OS (P<O.O I or. 0.05), while viscosity (Spinnbarkiet) was significantly higher (P<O.O I) in winter than in summer and autumn breeding seasons (Table 2). The' differences in ph and viscosity between summer and autumn were not significant. ER was higher significantly (P<O.O I) in summer than in autumn season. Ferning arborization values were not significantly affected by breeding season. These results agreed with the findings of EI-Darawany (I 994). Cervical mucus components The cervical mucus glucose, inorganic phosphorus and zinc were significantly lower (P<O.OI) in ewes during summer than in winter and autumn seasons (Table 3). This may be due to the high ambient temperature in summer than in winter and autumn seasons. Conception and lambing rates The conception rate was significantly lower (P<0.05) in summer (THI = 25.6, Table 3. Least square means ( S.E) of cervical mucus components in Egyptian Suffolk ewes as affected by breeding season Variables Breeding season Significance Winter Summer Autumn Glucose (mg/dl) 7.2S a ± b ± S a ± 0.49 ** Inorganic phosphorus (ngldl) 7.40 a ±O c ±0.20 S.29 b ±0.20 ** Zinc (% g1dl) IOS.OSa± b ± Ola±2.93 ** Means bearing different letters within the same row. differ significantly (P<O.O I). * * P<O.O I. The increase in viscosity and decrease of ph and ER in ewes cervical mucus during winter (THI = 14.5; no heat stress) than in summer and autumn seasons may be due to the increase in ambient temperature in the latter two seasons (THI = 25.6 and 24.7 were very severe and severe heat stress, respectively). with daylight length hours) breeding season than in autumn (THI = 24.7, with daylight length 12.20) and winter (THI = 14.5, with daylight length hours) (Table 4). This may be due to the exposure to more high arilbient temperature during summer than in winter and autumn seasons. These results were in agreement with those

5 EGYPTIAN SUFFOLK EWES ISI Table 4. Least square means (SE) of conception and lambing rates in Egyptian Suffolk ewes as affected by breeding season Variables Conception rate (ewes conception/ewes joined %) Lambing rate (lambs born/ewes lambed %) Means bearing different letter within ** (P<O.OI), NS = Not significant. Breeding season Winter Summer Autumn a ± b ± a ±8.26 IOO.OO±8.50 IOO.OO± ±13.80 the same raw, differ significantly (P<O.OI). Significance ** NS obtained by Hafez (I987) and Aboul-Naga (1987). Aboul-Naga et al. (I987 and 1988) found negative relationships in sheep between each of ambient temperature and daylight length and conception rate in Egypt. High environmental temperature or rapid and sudden fluctuations of temperature that often occur in many parts of the sub-tropics, cause unfavourable effects on reproductive function. For example high ambient temperature reduces the length of oestrus cycle or suppresses oestrus and adversely affects ovulation (Casu et al., 1991). Failure of ova to be fertilized and embryonic mortality may also occur during remating of ewes during hot weather. Due to this a large number of abnormal ova are produced and, only a small number of them is fertilized during summer. The latter phenomenon may be probably due to altered nucleic acid metabolism in ova subjected to a high temperature at a certain stage of development (for instance, the zygote). The critical period at which heat stress affects fertility is from a few days prior to and a few days after mating (Curtis, 1983). High ambient. temperature also affects uterine environment either directly by reducing blood supply (Sulong, 1987) or indirectly due to an imbalance of hormones such as progesterone, thyroid and glucocorticod hormones (Curtis, 1983). Lublin et al. (1984) clarified that, during hyperthermia, there were significant reductions in blood flow in the ovaries (-23%) and in the undifferentiated uterine wall of non-pregnant or early-pregnant animals. Such results verify that the low reproductive performance during periods of thermal stress is due to functional problem in females (as well as in males). Lambing rate was lower in winter and summer than in autumn breeding season, but the differences were not significant (Table 4). Efficacious and non-efficacious progesterone hormone The level of progesterone hormone in urine (efficacious) in ewes at 2] days after mating was significantly higher (P<O.05) in summer than in winter and autumn breeding seasons (Table 5). The efficacious progesterone (pregnandiol) is the chief excretory product of progesterone. The non-efficacious progesterone level is obtained by subtracting the progesterone value in urine from its corresponding progesterone value in plasma. Presence of the efficacious progesterone in the urine indicates a progestational endometerium and the increase of

6 182 MARAI et at. Table 5. Least square means (±S.E) of progesterone in blood and urine efficacious and non-efficacious progesterone in Egyptian Suffolk ewes as affected by breeding season Variables Breeding seasons Significance Progesterone hormone (Ilg/m I) In Blood at Winter Summer Autumn Pre-ostrus period 2.37± ± ±0.55 NS Oestrus period 1.46± I3± ±0.36 NS 21 st day after mating 3.47± ± ±2.13 NS In urine (efficacious) at Pre-ostrus period 0.99± ± ±0.11 NS Oestrus period 0.63± ± ±0.22 NS 21st day after mating 1.46 b ± a ± b ±1.58 * Non-efficacious progesterone ** at Pre-ostrus period 1.38± ± ±0.47 NS Oestorus period 0.83± ± ±0.24 NS 21st day after mating 2.01± ± ±0.97 NS Means bearing different letters within the same row, differ significantly (P<0.05). P<0.05 and NS = Not significant. ** Non-efficacious progesterone = Total - efficacious. efficacious progesterone concentration accelerates lambing rate. References Aboul-Naga, A.I The role of aldosterone in improving productivity of heat-stressed farm animals with different techniques. Ph.D. Thesis, Faculty of Agriculture, Zagazig University, Zagazig, Egypt. Aboul-Naga, A.M., Aboul-Ela, M.B. and Mansour. H Seasonality of breeding activity in sub-tropical Egyptian sheep breeds. Proceedings of 38th Annual Meeting EAAP, Lisbon. Portugal. Aboul-Naga. A.M.. Hassan, F. and Aboul-Ela, M.B Reproductive performance 0'- local Egyptian sheep and goat breeds and crosses with imported temperate breeds "Philoetio". Symposium on the Evaluation of Mediterranean Sheep and Goats, Santarem, Portugal. AOAC Association of Official Agriculture Chemists. Official Methods of Analysis. Washington, DC. Aboul-Naga, A.M. and Aboul-Ela, M.B The perlixmance of Egyptian breeds of sheep. European breeds and their crosses. 2. European breeds and their crosses. Proceedings of 3(jh Annual Meeting of the European Association for Animal Production, Kallithea. Greece. pp AOAC Official Methods of Analysis. Washington, DC. Casu. So, CappaL P. and Naitona. S Effects of high temperature on reproduction in small ruminants. Animal HusbandlY in Warm Climates. No. 55. EAAP Publication. pp Curtis. S.L Environmental Management in Animal Agriculture. State University Press. Amcs. USA. Daadcr. A.II.. EI-Keraby. Fo, Marai. I.F.M and EI-.Iibouri. S.A.H Ram scmen characteristics as affected hy some climate clements in sub-tropical conditions. cgyptian Journal of Animal Production 25( I): EI-Darawany. A.A High and low litter size trait and its relationships with serum and urine progesterone. serum zinc and serum phosphorus in New Zealand White rahhits and improvement lilr the low litter size trait. Tropenlandwirtshafi 30:

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