- Email: [email protected]
Reproductive management of hair sheep with progesterone and gonadotropins in the tropics
Small Ruminant Research 27 Ž1998. 237–242
Reproductive management of hair sheep with progesterone and gonadotropins in the tropics J. Rosado a , E. Silva
b,)
, M.A. Galina
a,b,c
a
c
PICP Posgrado Interinstitucional en Ciencias Pecuarias, UniÕersidad de Colima, AP. 22 Colima, Colima, Mexico 28000 ´ b CUIDA, UniÕersidad de Colima, AP. 22 Colima, Colima, Mexico 28000 ´ Departamento de Ciencias Pecuarias, Facultad de Estudios Superiores Cuautitlan, ´ UNAM, Cuautitlan ´ Izcalli, Edo de Mexico, ´ Mexico 54700 ´ Accepted 20 December 1996
Abstract A study was conducted at a farm near Colima, Mexico, to evaluate the reproductive performance of 60 hair sheep and 30 F1 crossbreds ŽRambouillet or Dorset = Rambouillet. with progesterone and gonadotropin treatments. Sheep grazing was supplemented with a protein bank of Leucaena leucocephala. Ewes were supplied with a concentrate of 3 Mcal MErkg and 18% CP 1 month before and 1 month after lambing. Oestrus synchronization or induction was performed with progesterone and gonadotropins. Females were bred 48–69 h after sponge retrieval. Of the treated sheep 97% showed oestrus. Average fertility was 66%. Seasonally low lambing rate was from March to July in the absence of hormone treatments. Hormone treated sheep Žhair sheep and crossbreds. showed increased Ž P - 0.01. fertility in 8 out of 12 months. Higher difference in fertility was due to treatment in January to May. Fertility was highest from June to December. Overall prolificacy of treated ewes was 1.93 " 0.32 versus 1.79 " 0.21 for controls. Hormone treated ewes had a greater percentage of twins, triplets and quadruplets than controls. Overall yield of lambs from treated ewes was 29.86 kg per year compared to 19.99 kg for controls, however since controls had more single lambs, overall birth weight was in favour of controls Ž2.20 versus 1.85.. It is concluded that crosses of Rambouillet or Rambouillet= Dorset males with Pelibuey and Barbados Blackbelly hair ewes increased lamb crop, birth weight, and number of parturitions per ewe per year under tropical conditions in Mexico. q 1998 Elsevier Science B.V. Keywords: Reproduction; Hair sheep; Gonadotropins; Progesterone
1. Introduction Tropical hair sheep have been an important source of meat in many countries in Latin America ŽFitzhugh and Bradford, 1983.. The hair sheep of Mexico ) Corresponding author. Universidad de Colima, 25 de Julio a965, Colima, Mexico 28045. Tel.: 52-331-41133; fax: 52-331´ 27581; e-mail: [email protected]
are mainly Pelibuey and Barbados Blackbelly. The Pelibuey breed predominates and makes up 90–95% of the total hair sheep population in Mexico, which amounts to approximately 500,000 ŽGonzalez-Reyna ´ et al., 1991.. Sheep reproductive activity is seasonally regulated by photoperiod ŽSanchez et al., 1995; Schan´ bacher, 1980; Williams, 1984; Gonzalez-Reyna et ´ al., 1991; Cruz et al., 1994.. Seasonality of reproduc-
00921-4488r98r$19.00 q 1998 Elsevier Science B.V. All rights reserved. PII S 0 9 2 1 - 4 4 8 8 Ž 9 7 . 0 0 0 3 7 - 0
238
J. Rosado et al.r Small Ruminant Research 27 (1998) 237–242
tion is a common feature in sheep and goat breeds in temperate latitudes but less marked in the tropics, where all year round breeding is practiced ŽGonzalez-Reyna et al., 1991; Valencia and Gonza´ lez, 1983; Galina et al., 1992a; Galina et al., 1992b. In other studies, estrous cycles seemed to be present all year, fertility ranged from 70–90% and prolificacy varied from 113–144 lambs born from 100 ewes exposed ŽValencia and Gonzalez, 1983; Valencia et al., 1981.. Photoperiod does not seem to be the main factor responsible for seasonal breeding in the Pelibuey ewe. Instead, other factors such as nutrition and possibly relative humidity, precipitation, temperature and grass digestibility may have a more direct effect on periods of reduced cyclicity during the months of February to April ŽOrtega et al., 1981; Trejo, 1984; Gonzalez-Reyna et al., 1991.. The ma´ jority of lambing by wool breeds in Mexico is in autumn and winter when photoperiod is slightly shorter ŽTempest and Boaz, 1973; Sanchez et al., ´ 1995.. Seasonality in Pelibuey sheep has been found to be mostly from January to April ŽValencia, 1985; Galina et al., 1992a; Galina et al., 1992b.. Pelibuey sheep had 70–97% fertility, prolificacy was 1.0–1.4 and average live weight of lambs was 2.0–2.9 kg ŽGonzalez-Reyna et al., 1991; Valencia, 1985; Galina ´ et al., 1992b.. However, in Mexico, changes in length of photoperiod during the year are small, because of the tropical geographical latitude, therefore reproduction anoestrus length is shorter when compared to temperate regions ŽSerratos et al., 1985; Valencia, 1985; Gonzalez-Reyna et al., 1991; Galina et al., 1992a; ´ Galina et al., 1992b.. Previous studies have shown the possibility of managing improved reproduction of sheep with different hormone treatments such as corticosteroids, prostaglandins, progesterone and gonadotropins, but with different results because of influencing factors such as reproductive stage, environmental factors, length of postpartum period, lactation number, litter size and others ŽWheaton et al., 1993; Alvarez et al., 1994; Castillo et al., 1981; Hulet and Stormshak, 1972; Restall et al., 1978; Quispe et al., 1994.. Work in the tropics with Pelibuey females and males of the heavy wool breed Rambouillet or crossbreds has shown that improved body weight and daily gain can be achieved by using synchronization
Fig. 1. Average fertility in terms of monthly percentage of ewes conceived per ewes exposed to males; hormone treated compared to controls.
or induction of oestrus and taking advantage of hybrid vigour and heterosis ŽGalina et al., 1992a; Galina et al., 1992b: Velazquez, 1994.. ´ The objectives of this study were to induce or synchronize oestrus in Mexican hair sheep and in F1 crossbred ŽDorset = Rambouillet, Rambouillet. sheep all year round, with progesterone and gonadotropins to accelerate reproductive performance and spread lambing over several months for greater economic returns.
2. Materials and methods The study was conducted near Colima, Mexico. The farm is located at 19813X latitude N and 104848X longitude W, at 550 m above sea level. The climate is classified as dry tropics with rain from June to October, average temperature 258C, with a minimum of 178C and maximum of 308C. There is an average rain precipitation of 850 mm per year, minimum relative humidity 56% and maximum 80% ŽGarcıa, ´ 1973..
Fig. 2. Effect of hormone treatment on percent fertility by seasons.
J. Rosado et al.r Small Ruminant Research 27 (1998) 237–242 Table 1 Prolificacy Žnumber of lambs per ewe exposed. by seasons Season
Controls
Hormone treated
F1 Crossbreds Hair sheep F1 Crossbreds Hair sheep Spring Summer Autumn Winter Overall
2.33 1.80 1.65 1.69
1.86 1.67 1.67 1.72 1.79"0.21
2.75 2.02 1.80 1.75
1.85 1.65 1.72 1.90 1.93"0.32
239
performance was recorded by incidence of lambing, seasonal distribution of fertility calculated and lambing interval determined. The study was subdivided into 4 lambing seasons: Ž1. January to March, Ž2. April to June, Ž3. July to September, and Ž4. October to December. Statistical analyses were performed by the Xi-square method.
3. Results Sheep grazing was supplemented with a protein bank, consisting of Leucaena leucocephala restricted grazing. Females 1 month before and 1 month after lambing were supplied with a concentrate containing 3 Mcal MErkg and 18% CP. Regular deworming was performed depending on season and rainfall. A total of 60 Pelibuey or Barbados Blackbelly sheep or their crosses were studied. Females were bred with Rambouillet or Dorset x Rambouillet males. Synchronization or oestrus induction was performed with the INRA method modified with prostaglandin administration Ž500 IU im. PMSG. and 2.5 mg im PGF2a ŽGalina et al., 1992a; Galina et al., 1992b.. Females were exposed to males 48–69 h after sponge retrieval. New born lambs were weighed and adult females were synchronized at 45 day post-partum to obtain early pregnancy, trying to obtain two parturitions per year or three every 2 years. Monthly reproductive
Of the treated sheep 97% showed oestrus. Average fertility was 66%. Seasonal lambing was reduced from March to July but had peaks in February and June. The hormone treated sheep Žhair sheep and crossbreds. showed a significant increase Ž P - 0.01. in fertility in 8 out of 12 months ŽFig. 1.. Highest difference in fertility due to treatment was obtained from January to May, but highest overall fertility was observed from June to December. Seasonal fertility for the hormone treated sheep was 53.5, 63.3, 70.3, and 74% for spring, summer, autumn and winter compared to controls being 37.6, 72.6, 70.0, and 25.0, respectively ŽFig. 2.. Overall prolificacy of treated ewes was 1.93 " 0.32, compared to controls which was 1.79 " 0.21 ŽTable 1.. Hormone treated ewes had a greater percentage of twins, triplets and quadruplets ŽTable 2. than controls. Overall yield of lambs from treated ewes was 29.86 kg per year compared to 19.99 kg for the controls. However since controls had more
Table 2 Effects of hormone treatments compared to controls on birth weights and distribution of single, twins, triplets and quadruplets for F1 crossbreds with wool sheep ŽRambouillet or Rambouillet= Dorset. and hair sheep ŽPelibuey and Barbados Blackbelly. Treatment Treated Control
Treated Control a,b
Birth weight, kg F1 Crossbreds Hair sheep F1 Crossbreds Hair sheep Percentage of all lambs F1 Crossbreds Hair sheep F1 Crossbreds Hair sheep
Ž P - 0.05.. A,B, C,D Ž P - 0.01..
Single
Twins
Triplets
Quadruplets
Overall totals
Overall average
3.26 2.63 3.00 2.50
2.51 1.88 2.63 1.99
1.70 1.51a 1.75 0.00 b
1.39 a 0.00 0.00 b 0.00
18.94 29.86 10.92 13.51 19.99 6.48
1.89 1.82 2.25 2.16
21.5A 21.1C 62.0B 72.0D
45.4A 63.1C 26.0B 28.0D
19.8A 15.8C 12.0 0.00D
13.3A 0.00 0.00B 0.00.
240
J. Rosado et al.r Small Ruminant Research 27 (1998) 237–242
single lambs average birth weight overall was in favour of controls Ž2.20 versus 1.85..
4. Discussion Results of this study showed distinct seasonality in hair sheep, with 16% fertility during March, April and May but this was significantly improved by hormone treatments ŽFig. 1.. Valencia Ž1985. reported 17% in April. This seasonality has been found even when sheep were kept at a high nutritional niveau all year ŽHeredia et al., 1991.. Other work has shown acceptable all year round fertility when NRC nutritional requirements were met ŽCastillo et al., 1972.; however, most studies in the Mexican tropics found some seasonality ŽGalina et al., 1992a; Galina et al., 1992b.. Overall fertility in the present study Ž66%. was less than in the work of Valencia Ž1985. and Olazaran ´ and Lagunes Ž1988., who reported 70–90%, but they conducted their studies in experiment stations with supplementary feeding, while in this study mainly grazing with low supplementation levels was used. Prolificacy of 1.79 lambs per ewe for control ewes and 1.93 for hormone treated ewes Žhair sheep and crossbreds combined. in this study was greater than in most other reports ŽCastillo et al., 1972; Olazaran ´ and Lagunes, 1988; Valencia, 1985; Gonzalez-Reyna et al., 1991; Peron, ´ ´ 1985; Peron ´ et al., 1991; Galina et al., 1992a; Galina et al., 1992b.. Gonadotropin hormone treatment increases ovulation ŽGalina et al., 1992b.. Average lamb birth weight was higher for crossbreds Ž2.07 kg. than for Pelibuey Ž1.99 kg.. Comparing single lambs, crossbreds had a higher birth weight Ž3.13 versus 2.56 kg.. Previous reports gave similar results ŽValencia et al., 1975; Pena, ˜ 1976; Olazaran ´ and Lagunes, 1988; Martinez et al., 1987.. However, total lamb weight yield per year was significantly higher for hormone treated ewes compared to the negative controls Ž29.86 versus 19.99 kg..
5. Conclusions Hormone treatment with the INRA method combined with the use of Rambouillet or Rambouillet=
Dorset males to Pelibuey and Barbados Blackbelly hair ewes increased lamb crop, birth weight, and number of parturition per ewe per year, under tropical conditions in Mexico. Crossbred ewes Žhair sheep = Rambouillet males; hair sheep = DorsetRambouillet males. produced heavier lamb birth weights than Pelibuey ewes.
6. Unlinked References Martinez et al., 1979, Pau and Aguade, ´ 1983, Pena et al., 1984, Rajamahendran et al., 1993, Va˜ lencia et al., 1977, 1978
Acknowledgements Many thanks are due to DGAPA, UNAM. Grants IN 501595, CONACYT Grant 3108-N and SISMORELOS Grant 9501075 for support of this study.
References Alvarez, A., Rodriguez, O., Hernandez, J., 1994. Sincronizacion ´ ´ del estro en la borrega Pelibuey con la Utilizacion ´ de Prostaglandina F2 a. ŽOestrus synchronization in Pelibuey sheep with prostaglandins. Tec. Pec. Mex. ´ Vol. 32, 21–29. Castillo, R.H., Roman, H., Rojas, J., Lozano, F., Martinez, P., 1981. Induccion ´ del parto en borregas Tabasco ŽLambing induction in Tabasco sheep.. XV Reunion ´ Anual del INIP Mexico, pp. 103-105. Castillo, R.H., Valencia, J., Berruecos, J.M., 1972. Comportamiento reproductivo del borrego Tabasco mantenido en clima tropical y subtropical. I. Indices de fertilidad. ŽReproductive performance of Tabasco sheep in the tropics and subtropics. 1. Fertility index. Tec. ´ Pec. Mex. ´ 20, 52–56. Cruz, L., Fernandez-Baca, S., Alvarez, J.A., Perez, H. 1994. ´ ´ Variaciones estacionales en presentacion ´ de ovulacion, ´ fertilizacion ´ y sobrevivencia embrionaria de ovejas Tabasco en el ŽSeasonal variations in oestrus presentation, tropico humedo ´ ´ ovulation, fertilization and embryo survival in Tabasco sheep in the humid tropics.. Vet. Mex. ´ 25 Ž1.. Fitzhugh, H.A., Bradford, G.E. ŽEds.., 1983. Hair Sheep of Western Africa and the Americans, Winrocks International. Westview Press, Boulder, CO, pp. 257-274. Galina, M., Silva, E., Guerrero, M., Aguilar, A., 1992a. Comportamiento Reproductivo del borrego Tabasco y Black Belly bajo pastoreo diurno en el Tropico seco Mexicano en Colima ´ ŽReproductive performance of Tabasco and Black Belly sheep
J. Rosado et al.r Small Ruminant Research 27 (1998) 237–242 grazing in the dry tropics of Colima.. Avances en Investigacion ´ Agropecuaria 1 Ž1., 118-129. Galina, M., Silva, E., Aguilar, A. 1992b. Habilidad reproductiva del borrego Tabasco en Colima. ŽReproductive performance of Tabasco sheep in Colima. V Reunion ´ de Avances en Investigacion ´ Agropecuaria 92, 59-62. Garcıa, ´ E. 1973. Modificacion ´ al sistema de clasificacion ´ climatica ´ de Koppen ŽModifications of Koppen climate classification system.. Instituto de geografia, Universidad Nacional ´ Autonoma de Mexico, Mexico, D.F. p. 33. ´ ´ ´ Gonzalez-Reyna, A., Valencia, J., Foote, W.C., Murphy, B.D., ´ 1991. Hair sheep in Mexico: Reproduction in the Pelibuey sheep. Anim. Breed Abstr. 59, 509–524. Heredia, A.M. Velazquez, M.A., Quintal, F.J., Mex, R.J., Aragon, ´ ´ G.A., 1991. Effecto de dos fuentes de alimentacion ´ sobre la estacionalidad reproductiva de la oveja Polibuey ŽEffect of two feed sources in response to reproductive seasonality.. Memorias de la Reunion ´ de Investigacion ´ Pecuaria on Mexico. ´ Ciudad Victoria, Tamaulipas. SARH-UNAM. p. 96. Hulet, C.V., Stormshak, F., 1972. Some factors affecting response of anestrous ewes to hormone treatment. J. Anim. Sci. 34 Ž6., 1011–1019. Martinez, A., Bores, R., Castellanos, A. 1987. Zoometria y prediccion ´ de la composicion ´ corporal de la borrega Pelibuey ŽZoometrics and body composition prediction in Pelibuey sheep.. Tec. ´ Pec. Mex. ´ 25 Ž1., 72–84. Martinez, P., Ruiz, R., Castillo, H., 1979. Sincronizacion ´ del estro en borregas Tabasco o´ Pelibuey ŽOestrus synchronization in Tabasco and Pelibuey sheep.. Tec. ´ Pec. Mex. ´ 36, 28–32. Pena, ˜ F., 1976. Cria y explotacion ´ del borrego Tabasco. ŽNursing and production of the Tabasco sheep.. Primer dia del ganadero. Centro Experimental Pccuario Tizimin, INIP-SAG, 1-28. Ortega, E., Acosta, C., Gonzalez, A., de Alba, J. 1981. Edad al ´ primer parto y frecuencia reproductiva en ovinos de pelo ŽAge at first lambing and reproductive performance of hair sheep. Memorias ALPA. Santo Domingo, Rep. Dominicana. 16:44, 135. Olazaran, ´ J.S., Lagunes, L., Castillo H. 1988. Indices productivos y reproductivos en un modulo con ovinos Pelibuey en clima subtropical ŽReproductive and productive performance in Pelibuey sheep under subtropical conditions.. INIFAP-SARH. Memorias de la XI Reunion de la Asociacion Latinoamericana de Produccion Animal. La Habana, Cuba, p. 122. Pau, J.J., Pijoan Aguade, ´ 1983. Aspectos endocrinos en diversas fases reproductivas de las ovejas. 1. Ciclo Estral. Estudio Recapitulativo ŽEndocrine management of reproduction of sheep. Oestrus cycle. Literature Review.. Vet. Mex. ´ 14 Ž4., 229-234. Pena, J.J., Ruiz, R., Villareal, M., Avila, A., 1984. ˜ F., Hernandez, ´ Utilizacion ´ de Acetato de Fluorogestona impregnada en esponjas intravaginales e implantes subcutaneos usados de SC 21009 ´ para la sincronizacion ´ del estro en borregas Romney Marsh. ŽUse of fluorogestone acetate intravaginal sponges or subcutaneous implants with SC 21009 to synchronize oestrus in Romney Marsh sheep.. Tec. ´ Pec. Mex. ´ 47, 82–87. Peron, ´ N., 1985. Bases fundamentales para el manejo de la produccion ´ de carne del ovino Pelibuey en Cuba ŽFundamental bases for management of Pelibuey sheep meat production in
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Cuba.. Memorias del curso de actualizacion ´ Produccion ´ de ovinos en zonas tropicales. CIEEGT. UNAM. Sep. 1985. Tlapacoyan, Ver. Mex. ´ 45, 59. Peron, ´ N., Lima, T., Fuentes, J.L., 1991. El ovino Pelibuey de Cuba. Revision de algunas caracterısticas produc´ bibliografica ´ ´ tivas ŽCuban Pelibuey sheep: bibliographical review of some production characteristics.. Rev. Mundial Zootecnia 66, 32–39. ´ Quispe, Q.T., Zarco, L., Valencia, J. 1994. Control artificial de la reproduccion ´ en la oveja. ŽArtificial control of reproduction in sheep.. Memorias del curso de actualizacion ´ en ovinos. UAEM-FESC UNAM. Toluca, Mex., ´ pp. 59-70. Rajamahendran, J., Raniowski, J., Ravindran, V., 1993. Effects of PMSG and ram contact on the reproductive performance of progestagen-treated ewes during breeding and anestrous season. Small Ruminant Res. 10, 341–347. Restall, B.J., Kearins, A., Herdegen, J., Carberry, P., 1978. The induction of reproductive activity in lactating ewes. Austr. J. Agr. Res. 29, 181–187. Sanchez, V., Fuentes, V., Gonzalez, H., Perera, C., Salas, A., ´ ´ 1995. El efecto de la Naloxona en primera y segunda dosis sobre la secrecion ´ pulsatil de la LH en borrega Criolla durante su anestro ŽEffect of first and second aplication of naloxone in LH scretion in Criollo sheep during anoestrus.. Memorias del XIX Congreso Nacional de Buiatrıa, ´ Torreon, ´ Coahuila, Mex., ´ pp. 507-514. Schanbacher, B., 1980. Relationship of daylength and prolactin to resumption of reproductive activity in anestrous ewes. J. Anim. Sci. 50 Ž2., 293–297. Serratos, G., Garcıa, ´ E., Valencia, J., 1985. Estacionalidad reproductiva, tasa de ovulacion de la gestacion ´ y caracterısticas ´ ´ de la oveja criolla ŽReproductive seasonality, ovulation rate and pregnancy characteristics of Criollo sheep.. Vet. Mex. ´ 16, 179–183. Tempest, W.N., Boaz, T.G., 1973. The seasonality of reproductive performance of Merino sheep in Britain. Anim. Prod. 17, 33-41. Trejo, A., 1984. Estacionalidad del macho ovino ŽSeasonality of Pelibuey male.. Memorias del curso Bases de la Crıa ´ Ovina. Toluca, Mex. ´ Valencia, M., 1985. Fisiologıa ´ reproductiva del ovino Pelibuey ŽReproductive physiology of Pelibuey sheep.. Memorias del curso de actualizacion ´ Produccion ´ de ovinos en zonas tropicales. CIEEGT. UNAM. Tlapacoyan, Ver. Mex., ´ pp. 37-44. Valencia, M., Castillo, H., Berruecos, J.M., 1975. Reproduccion ´ y manejo del borrego Tabasco o´ Pelibuey ŽManagement and reproduction of Tabasco or Pelibuey sheep.. Tecnica Pecuaria ´ Mexico. 29, 66–72. ´ Valencia, M., Gonzalez, P.E., 1983. Pelibuey sheep in Mexico. In: Fitzhugh, H.A., Bradford, G.E. ŽEds.., Hair sheep of Western Africa and the Americas. Winrock International, Westview Press, Boulder, CO, p. 319. Valencia, M., Heredia, M. and Gonzalez, E. 1981. Estacionalidad ´ reproductiva en la oveja Pelibuey ŽReproductive seasonality in Pelibuey sheep.. Memorias XV Reunion ´ Anual, INIP, pp. 34-38. Valencia, J., Barron, S., 1977. Pubertad en ´ C., Fernandez-Baca, ´ corderos Tabasco x Dorset ŽPuberty in Tabasco=Dorset lambs.. Vet. Mex. ´ 8, 127–130.
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Valencia, J., Barron, S., Huerta, N., 1978. ´ C., Fernandez-Baca, ´ Variaciones estacionales en la presentacion ´ del estro en ovejas ŽSeasonal variations in oestrus Dorset y Criollas en Mexico ´ performance of Dorset and Criollo sheep in Mexico.. Veterinaria, Mex. ´ Ž9., 45-50. Velazquez, A., 1994. Cruzamiento de ovinos de razas tropicales ´ con razas de clima templado. ŽCrossbreeding among tropical sheep and temperate wether breeds.. Memorias del curso de actualizacion ´ en Ovinos. FESC UNAM. Toluca, Edo. Mex., ´ Mex. ´ 165, 173.
Wheaton, J.E., Carlson, K.M., Windels, H.F., Johnston, L.J., 1993. CIDR: A new progesterone-relasing intravaginal device for induction of estrus and cycle control in sheep and goats. Anim. Reprod. Sci. 33, 127–141. Williams, H. 1984. Efecto de la latitud en la estacionalidad reproductiva de las ovejas ŽEffect of latitude on reproduction seasonality in sheep.. Memorias del Curso ‘Bases de la Crıa ´ Ovina’. Toluca, Mex. ´
Reproductive management of hair sheep with progesterone and gonadotropins in the tropics J. Rosado a , E. Silva
b,)
, M.A. Galina
a,b,c
a
c
PICP Posgrado Interinstitucional en Ciencias Pecuarias, UniÕersidad de Colima, AP. 22 Colima, Colima, Mexico 28000 ´ b CUIDA, UniÕersidad de Colima, AP. 22 Colima, Colima, Mexico 28000 ´ Departamento de Ciencias Pecuarias, Facultad de Estudios Superiores Cuautitlan, ´ UNAM, Cuautitlan ´ Izcalli, Edo de Mexico, ´ Mexico 54700 ´ Accepted 20 December 1996
Abstract A study was conducted at a farm near Colima, Mexico, to evaluate the reproductive performance of 60 hair sheep and 30 F1 crossbreds ŽRambouillet or Dorset = Rambouillet. with progesterone and gonadotropin treatments. Sheep grazing was supplemented with a protein bank of Leucaena leucocephala. Ewes were supplied with a concentrate of 3 Mcal MErkg and 18% CP 1 month before and 1 month after lambing. Oestrus synchronization or induction was performed with progesterone and gonadotropins. Females were bred 48–69 h after sponge retrieval. Of the treated sheep 97% showed oestrus. Average fertility was 66%. Seasonally low lambing rate was from March to July in the absence of hormone treatments. Hormone treated sheep Žhair sheep and crossbreds. showed increased Ž P - 0.01. fertility in 8 out of 12 months. Higher difference in fertility was due to treatment in January to May. Fertility was highest from June to December. Overall prolificacy of treated ewes was 1.93 " 0.32 versus 1.79 " 0.21 for controls. Hormone treated ewes had a greater percentage of twins, triplets and quadruplets than controls. Overall yield of lambs from treated ewes was 29.86 kg per year compared to 19.99 kg for controls, however since controls had more single lambs, overall birth weight was in favour of controls Ž2.20 versus 1.85.. It is concluded that crosses of Rambouillet or Rambouillet= Dorset males with Pelibuey and Barbados Blackbelly hair ewes increased lamb crop, birth weight, and number of parturitions per ewe per year under tropical conditions in Mexico. q 1998 Elsevier Science B.V. Keywords: Reproduction; Hair sheep; Gonadotropins; Progesterone
1. Introduction Tropical hair sheep have been an important source of meat in many countries in Latin America ŽFitzhugh and Bradford, 1983.. The hair sheep of Mexico ) Corresponding author. Universidad de Colima, 25 de Julio a965, Colima, Mexico 28045. Tel.: 52-331-41133; fax: 52-331´ 27581; e-mail: [email protected]
are mainly Pelibuey and Barbados Blackbelly. The Pelibuey breed predominates and makes up 90–95% of the total hair sheep population in Mexico, which amounts to approximately 500,000 ŽGonzalez-Reyna ´ et al., 1991.. Sheep reproductive activity is seasonally regulated by photoperiod ŽSanchez et al., 1995; Schan´ bacher, 1980; Williams, 1984; Gonzalez-Reyna et ´ al., 1991; Cruz et al., 1994.. Seasonality of reproduc-
00921-4488r98r$19.00 q 1998 Elsevier Science B.V. All rights reserved. PII S 0 9 2 1 - 4 4 8 8 Ž 9 7 . 0 0 0 3 7 - 0
238
J. Rosado et al.r Small Ruminant Research 27 (1998) 237–242
tion is a common feature in sheep and goat breeds in temperate latitudes but less marked in the tropics, where all year round breeding is practiced ŽGonzalez-Reyna et al., 1991; Valencia and Gonza´ lez, 1983; Galina et al., 1992a; Galina et al., 1992b. In other studies, estrous cycles seemed to be present all year, fertility ranged from 70–90% and prolificacy varied from 113–144 lambs born from 100 ewes exposed ŽValencia and Gonzalez, 1983; Valencia et al., 1981.. Photoperiod does not seem to be the main factor responsible for seasonal breeding in the Pelibuey ewe. Instead, other factors such as nutrition and possibly relative humidity, precipitation, temperature and grass digestibility may have a more direct effect on periods of reduced cyclicity during the months of February to April ŽOrtega et al., 1981; Trejo, 1984; Gonzalez-Reyna et al., 1991.. The ma´ jority of lambing by wool breeds in Mexico is in autumn and winter when photoperiod is slightly shorter ŽTempest and Boaz, 1973; Sanchez et al., ´ 1995.. Seasonality in Pelibuey sheep has been found to be mostly from January to April ŽValencia, 1985; Galina et al., 1992a; Galina et al., 1992b.. Pelibuey sheep had 70–97% fertility, prolificacy was 1.0–1.4 and average live weight of lambs was 2.0–2.9 kg ŽGonzalez-Reyna et al., 1991; Valencia, 1985; Galina ´ et al., 1992b.. However, in Mexico, changes in length of photoperiod during the year are small, because of the tropical geographical latitude, therefore reproduction anoestrus length is shorter when compared to temperate regions ŽSerratos et al., 1985; Valencia, 1985; Gonzalez-Reyna et al., 1991; Galina et al., 1992a; ´ Galina et al., 1992b.. Previous studies have shown the possibility of managing improved reproduction of sheep with different hormone treatments such as corticosteroids, prostaglandins, progesterone and gonadotropins, but with different results because of influencing factors such as reproductive stage, environmental factors, length of postpartum period, lactation number, litter size and others ŽWheaton et al., 1993; Alvarez et al., 1994; Castillo et al., 1981; Hulet and Stormshak, 1972; Restall et al., 1978; Quispe et al., 1994.. Work in the tropics with Pelibuey females and males of the heavy wool breed Rambouillet or crossbreds has shown that improved body weight and daily gain can be achieved by using synchronization
Fig. 1. Average fertility in terms of monthly percentage of ewes conceived per ewes exposed to males; hormone treated compared to controls.
or induction of oestrus and taking advantage of hybrid vigour and heterosis ŽGalina et al., 1992a; Galina et al., 1992b: Velazquez, 1994.. ´ The objectives of this study were to induce or synchronize oestrus in Mexican hair sheep and in F1 crossbred ŽDorset = Rambouillet, Rambouillet. sheep all year round, with progesterone and gonadotropins to accelerate reproductive performance and spread lambing over several months for greater economic returns.
2. Materials and methods The study was conducted near Colima, Mexico. The farm is located at 19813X latitude N and 104848X longitude W, at 550 m above sea level. The climate is classified as dry tropics with rain from June to October, average temperature 258C, with a minimum of 178C and maximum of 308C. There is an average rain precipitation of 850 mm per year, minimum relative humidity 56% and maximum 80% ŽGarcıa, ´ 1973..
Fig. 2. Effect of hormone treatment on percent fertility by seasons.
J. Rosado et al.r Small Ruminant Research 27 (1998) 237–242 Table 1 Prolificacy Žnumber of lambs per ewe exposed. by seasons Season
Controls
Hormone treated
F1 Crossbreds Hair sheep F1 Crossbreds Hair sheep Spring Summer Autumn Winter Overall
2.33 1.80 1.65 1.69
1.86 1.67 1.67 1.72 1.79"0.21
2.75 2.02 1.80 1.75
1.85 1.65 1.72 1.90 1.93"0.32
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performance was recorded by incidence of lambing, seasonal distribution of fertility calculated and lambing interval determined. The study was subdivided into 4 lambing seasons: Ž1. January to March, Ž2. April to June, Ž3. July to September, and Ž4. October to December. Statistical analyses were performed by the Xi-square method.
3. Results Sheep grazing was supplemented with a protein bank, consisting of Leucaena leucocephala restricted grazing. Females 1 month before and 1 month after lambing were supplied with a concentrate containing 3 Mcal MErkg and 18% CP. Regular deworming was performed depending on season and rainfall. A total of 60 Pelibuey or Barbados Blackbelly sheep or their crosses were studied. Females were bred with Rambouillet or Dorset x Rambouillet males. Synchronization or oestrus induction was performed with the INRA method modified with prostaglandin administration Ž500 IU im. PMSG. and 2.5 mg im PGF2a ŽGalina et al., 1992a; Galina et al., 1992b.. Females were exposed to males 48–69 h after sponge retrieval. New born lambs were weighed and adult females were synchronized at 45 day post-partum to obtain early pregnancy, trying to obtain two parturitions per year or three every 2 years. Monthly reproductive
Of the treated sheep 97% showed oestrus. Average fertility was 66%. Seasonal lambing was reduced from March to July but had peaks in February and June. The hormone treated sheep Žhair sheep and crossbreds. showed a significant increase Ž P - 0.01. in fertility in 8 out of 12 months ŽFig. 1.. Highest difference in fertility due to treatment was obtained from January to May, but highest overall fertility was observed from June to December. Seasonal fertility for the hormone treated sheep was 53.5, 63.3, 70.3, and 74% for spring, summer, autumn and winter compared to controls being 37.6, 72.6, 70.0, and 25.0, respectively ŽFig. 2.. Overall prolificacy of treated ewes was 1.93 " 0.32, compared to controls which was 1.79 " 0.21 ŽTable 1.. Hormone treated ewes had a greater percentage of twins, triplets and quadruplets ŽTable 2. than controls. Overall yield of lambs from treated ewes was 29.86 kg per year compared to 19.99 kg for the controls. However since controls had more
Table 2 Effects of hormone treatments compared to controls on birth weights and distribution of single, twins, triplets and quadruplets for F1 crossbreds with wool sheep ŽRambouillet or Rambouillet= Dorset. and hair sheep ŽPelibuey and Barbados Blackbelly. Treatment Treated Control
Treated Control a,b
Birth weight, kg F1 Crossbreds Hair sheep F1 Crossbreds Hair sheep Percentage of all lambs F1 Crossbreds Hair sheep F1 Crossbreds Hair sheep
Ž P - 0.05.. A,B, C,D Ž P - 0.01..
Single
Twins
Triplets
Quadruplets
Overall totals
Overall average
3.26 2.63 3.00 2.50
2.51 1.88 2.63 1.99
1.70 1.51a 1.75 0.00 b
1.39 a 0.00 0.00 b 0.00
18.94 29.86 10.92 13.51 19.99 6.48
1.89 1.82 2.25 2.16
21.5A 21.1C 62.0B 72.0D
45.4A 63.1C 26.0B 28.0D
19.8A 15.8C 12.0 0.00D
13.3A 0.00 0.00B 0.00.
240
J. Rosado et al.r Small Ruminant Research 27 (1998) 237–242
single lambs average birth weight overall was in favour of controls Ž2.20 versus 1.85..
4. Discussion Results of this study showed distinct seasonality in hair sheep, with 16% fertility during March, April and May but this was significantly improved by hormone treatments ŽFig. 1.. Valencia Ž1985. reported 17% in April. This seasonality has been found even when sheep were kept at a high nutritional niveau all year ŽHeredia et al., 1991.. Other work has shown acceptable all year round fertility when NRC nutritional requirements were met ŽCastillo et al., 1972.; however, most studies in the Mexican tropics found some seasonality ŽGalina et al., 1992a; Galina et al., 1992b.. Overall fertility in the present study Ž66%. was less than in the work of Valencia Ž1985. and Olazaran ´ and Lagunes Ž1988., who reported 70–90%, but they conducted their studies in experiment stations with supplementary feeding, while in this study mainly grazing with low supplementation levels was used. Prolificacy of 1.79 lambs per ewe for control ewes and 1.93 for hormone treated ewes Žhair sheep and crossbreds combined. in this study was greater than in most other reports ŽCastillo et al., 1972; Olazaran ´ and Lagunes, 1988; Valencia, 1985; Gonzalez-Reyna et al., 1991; Peron, ´ ´ 1985; Peron ´ et al., 1991; Galina et al., 1992a; Galina et al., 1992b.. Gonadotropin hormone treatment increases ovulation ŽGalina et al., 1992b.. Average lamb birth weight was higher for crossbreds Ž2.07 kg. than for Pelibuey Ž1.99 kg.. Comparing single lambs, crossbreds had a higher birth weight Ž3.13 versus 2.56 kg.. Previous reports gave similar results ŽValencia et al., 1975; Pena, ˜ 1976; Olazaran ´ and Lagunes, 1988; Martinez et al., 1987.. However, total lamb weight yield per year was significantly higher for hormone treated ewes compared to the negative controls Ž29.86 versus 19.99 kg..
5. Conclusions Hormone treatment with the INRA method combined with the use of Rambouillet or Rambouillet=
Dorset males to Pelibuey and Barbados Blackbelly hair ewes increased lamb crop, birth weight, and number of parturition per ewe per year, under tropical conditions in Mexico. Crossbred ewes Žhair sheep = Rambouillet males; hair sheep = DorsetRambouillet males. produced heavier lamb birth weights than Pelibuey ewes.
6. Unlinked References Martinez et al., 1979, Pau and Aguade, ´ 1983, Pena et al., 1984, Rajamahendran et al., 1993, Va˜ lencia et al., 1977, 1978
Acknowledgements Many thanks are due to DGAPA, UNAM. Grants IN 501595, CONACYT Grant 3108-N and SISMORELOS Grant 9501075 for support of this study.
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