- Email: [email protected]
Comparison of Alpine and Nubian goats for some reproductive traits under dry tropical conditions
Small Ruminant Research 36 (2000) 91±95
Technical note
Comparison of Alpine and Nubian goats for some reproductive traits under dry tropical conditions L. Dickson-Urdanetaa, G. Torres-HernaÂndeza,*, C. Becerril-PeÂreza, F. GonzaÂlez-Cossioa, M. Osorio-Arcea, O. GarcõÂa-Betancourtb a
Colegio de Postgraduados, Montecillo, 56230, Mexico Fondo Nacional de Investigaciones Agropecuarias (FONAIAP), Ciae-Lara, Venezuela
b
Accepted 5 October 1999
Abstract The objective of this study was to compare some reproductive traits of Alpine and Nubian goats under an intensive management system in a dry tropical environment. Goats were kept under con®nement in half-covered pens and fed grass hay plus a commercial concentrate. Data were analyzed for kidding interval, proli®cacy and gestation length. No signi®cant (p > 0.05) breed effect was found for kidding interval; Alpine averaged 390.7 vs. 414.4 days for Nubian. There was, however, a signi®cant effect (p < 0.01) attributable to year of kidding; means ranged from 284 in 1989 to 590 days in 1994. Proli®cacy was signi®cantly affected (p < 0.01) by breed and year of kidding; Alpine and Nubians averaged 1.25 and 1.38 kids per parturition, respectively. Proli®cacy ranged from 1.53 in 1989 to 1.39 in 1994. A signi®cant (p < 0.01) breed effect on gestation length was found; means for Alpine and Nubians were 151.6 and 149.2 days, respectively. Kidding interval increased as years advanced, while proli®cacy decreased the ®rst 4 years of the study, thereafter began to increase. # 2000 Elsevier Science B.V. All rights reserved. Keywords: Goats; Reproductive ef®ciency; Intensive management; Climatic factors
1. Introduction In Venezuela there are 1.4 million goats raised mainly in arid and semiarid regions of the Lara, Zulia and Falcon States (Dickson and GarcõÂa, 1991). Most of the goats are raised under a prevailing extensive system, which involves limited feeding and sanitary practices and reproduction is never controlled. In early 1980s, a small group of farmers located in more * Corresponding author. Tel.: 595-20279; fax: 595-20279. E-mail address: [email protected] (G. Torres-HernaÂndez).
favorable areas of the country in term of feed supply decided to raise goats under more technical management conditions. To improve productive performance of native Criollo goats, farmers have used bucks of imported breeds such as Alpine, Nubian, Toggenburg, Saanen, and most recently Canarian, or to increase milk production and its by products have imported small herds of specialized dairy goats (mainly from USA). Kidding interval, proli®cacy and gestation length, among others, are traits in¯uenced by genetic, environmental, and management factors. They have eco-
0921-4488/00/$ ± see front matter # 2000 Elsevier Science B.V. All rights reserved. PII: S 0 9 2 1 - 4 4 8 8 ( 9 9 ) 0 0 1 3 0 - 3
92
L. Dickson-Urdaneta et al. / Small Ruminant Research 36 (2000) 91±95
nomic signi®cance since they determine reproductive performance (Terril and Foote, 1987) and the productivity of a goat enterprise. Accordingly, they might determine the preference of breeders for one breed over another within a production system. There is still limited information on reproductive performance of goats from temperate climate performing in the tropics (Chawla and Bhatnagar, 1984; Wilson and Murayi, 1988; Jan and Gupta, 1992; Mourad, 1993) and particularly in Venezuela. The present study was undertaken to estimate kidding interval, proli®cacy, and gestation length in a herd of Alpine and Nubian goats imported from the United States to Venezuela in 1988, and evaluate their reproductive performance when raised under intensive management. 2. Materials and methods 2.1. Animals and management Data for this study were collected from a goat herd founded initially with 133 does and their progeny maintained in facilities located at El CujõÂ State of Lara, northeast of Barquisimeto (108040 N and 698190 W). This region is a valley 420 m asl with average rainfall estimated at 586.9 mm and average temperature of 23.68C. The region is considered a very dry tropical forest. Data from 1988, the year of importation, were not included in the analysis since they were considered atypical. The herd was managed under intensive conditions. Goats were kept in six groups according to sex and physiological condition: (1) milking goats on; (2) dried and non-pregnant goats; (3) suckling kids; (4) goats in their last two months of gestation; (5) growing kids; and (6) bucks. Age of initial goats in the herd ranged from 1 to 2 years, and from 1990 on 15 yearling goats were incorporated each year to the breeding herd. Feeding consisted of a constant supply of Buffel (Cenchrus cilliaris) and Star grasses (Cynodon plectostachyus) given as hay. A high energy commercial concentrate ration with 17% CP was given at the rate of: 0.5 kg/day to open and growing females, 1 kg/day to does 2 months before parturition, 1.5 kg/day to milk producing does, 0.3 kg/day to bucks and ad libitum to suckling kids. A complete
mineral supplement and fresh water were always available. Osuji (1987) gave additional details on the feeding management. All goats were treated against internal parasites monthly, and were given dip baths against external parasites every 3 months. Goats were vaccinated against malignant edema, bacteridian carbon, hemorragic septicemia and tetanus. The reproductive management consisted of controlled mating after weaning. Does whose body weight exceeded 25.0 kg were exposed to males for the ®rst time. Bucks were kept in separate pens from females. Heat was detected using teaser bucks kept with the females year-round. Does in heat were exposed twice to a breeding buck selected according to breed and size. The following data were recorded: identi®cation of doe and buck, date of mating, weight of doe after parturition, sex and weight of kid, and date of kidding. Approximately, 10 different bucks were utilized every year. In 1989 and 1990, does were bred to 10 imported bucks; thereafter, bucks born and selected from the same herd were utilized, trying to avoid deliberate inbreeding. 2.2. Statistical analysis The General Linear Model procedures of the Statistical Analysis System were used (SAS, 1992). Data on kidding interval, proli®cacy, and gestation length were analyzed using a mixed model. Independent variables included in the model were breed of doe, doe nested within breed, year of kidding, season of kidding, type of kidding (except for proli®cacy) and the interaction between year of kidding and season of kidding. A preliminary analysis showed that the effect of age of doe was not signi®cant. Tukey's test was used to compare means (Steel and Torrie, 1980). 3. Results and discussion Differences between Alpine and Nubian were signi®cant for proli®cacy (p < 0.05) and gestation length (p < 0.01). Year of kidding had signi®cant effect on kidding interval (p < 0.05) and proli®cacy (p < 0.01). All other factors had non-signi®cant effects on the three traits studied.
L. Dickson-Urdaneta et al. / Small Ruminant Research 36 (2000) 91±95
93
Table 1 Least-squares means for kidding interval, proli®cacy and gestation length in a herd of Alpine and Nubian goats Trait
Kidding interval (day)
Prolificacy
Gestation length (day)
n
Mean
SE
n
Mean
SE
n
Mean
SE
120 66
390.7a 414.3a
15.3 21.5
178 94
1.25b 1.38a
0.04 0.05
151 79
151.6a 149.2a
0.27 0.33
23 59 42 24 18 20
284.4d 355.3c 370.1c 403.9b 411.4b 590.0a
36.6 25.3 26.6 36.5 43.3 70.6
31 78 66 39 28 30
1.53a 1.09d 1.32b 1.22c 1.33b 1.39b
0.11 0.06 0.06 0.09 0.11 0.13
30 71 56 29 20 24
150.8a 149.4a,b 149.9a 150.2a 149.3a,b 148.0b
0.64 0.46 0.43 0.59 0.76 0.70
Season of kidding Dry Rainy
74 112
407.5a 397.6a
24.8 19.2
108 164
1.34a 1.29a
0.05 0.05
100 130
149.1a 150.1a
0.35 0.35
Type of kidding Single Twin
109 77
396.2a 408.8a
18.7 22.9
± ±
± ±
± ±
152 78
149.9a 149.2a
0.30 0.44
Breed Alpine Nubian Year of kidding 1989 1990 1991 1992 1993 1994
a,b,c,d
Means within each class and in each column with different letters differ (p < 0.05).
3.1. Kidding interval Least-squares means for Alpine and Nubians were 390.7 and 414.3 days, respectively (Table 1). Lower values for this trait were found in the literature for both Alpine and Nubian breeds. Ali et al. (1983) reported 361 and 352 days, respectively, in the USA Chawla and Bhatnagar (1984) reported 364 days and Silva et al. (1998) reported 345 days for Alpine in India and Mexico, respectively. Whereas for Nubian, Jan and Gupta (1992) reported 337 days in India under intensive management. In Rwanda, Wilson and Murayi (1988) reported a kidding interval of 343 days in Small East African goats and its crosses with Anglo-Nubian and Alpine, and indicated that no signi®cant differences existed among these genotypes. GarcõÂa et al. (1977) mentioned that imported goats of European breeds have much longer kidding intervals (up to 100 more days). On the other hand, Sands and McDowell (1978) have indicated that European breeds performing in tropical conditions have kidding intervals very close to 1 year (345 days). Year of kidding had a signi®cant effect (p < 0.01) on kidding interval; least-squares means increased linearly from 284.4 days in 1989 to 411.4 in 1993 (Table 1). The sudden and unexpected increase observed in
1994 (590 days, cannot be reasonably explained other than the possibility of management and climate factors. Other authors have also found a signi®cant effect of year on kidding interval (Wilson and Light, 1986; Wilson and Murayi, 1988; Odubote, 1996). Generally, important changes in climatic conditions from one year to the next such as rainfall and temperature, as well as feeding and health practices, can be the main causes of year effect. 3.2. Proli®cacy Least-squares means for proli®cacy for Alpine and Nubian does were 1.25 and 1.38 kids/kidding, respectively (Table 1). A higher proli®cacy of Nubian does over that of Alpines (1.64 vs. 1.41) was also found by Jan and Gupta (1992) in India. Mourad (1993) reported an average of 1.45 for Alpine does, while Cabello et al. (1992) reported a value of 1.86 for Nubians. In Rwanda, Wilson and Murayi (1988) reported that differences in proli®cacy among SEA goat and its crosses with Anglo-Nubian and Alpine were not signi®cant (overall mean 1.75). Proli®cacy decreased from 1.53 in 1989 to 1.22 in 1992, and then increased to 1.33 in 1993 and 1.39 in 1994 (Table 1). Odubote (1996) found that litter size in
94
L. Dickson-Urdaneta et al. / Small Ruminant Research 36 (2000) 91±95
West African Dwarf goats was signi®cantly affected (p < 0.05) by year of kidding. 3.3. Gestation length Gestation length was 151.6 for Alpine and 149.2 for Nubian does (p < 0.01). Chawla and Bhatnagar (1984) showed that the differences between Alpine and Saanen does in gestation length were not signi®cant. However, Gangwar and Yadav (1987) reported a signi®cant effect (p < 0.05) of breed on gestation length when comparing four breeds of goats in India (mean 145.1 days). Montaldo et al. (1987) also found a signi®cant breed effect (p < 0.05) on gestation length in Alpine, Nubian, Saanen, Toggenburg and Granadina goats under stall feeding in Mexico; in that study, Alpine does had a longer gestation length (152 days) than Nubians (151 days). Similar differences between Alpine and Nubian were reported by Ali et al. (1983). Jan and Gupta (1992) found that gestation length of Alpine (151 days) was one-day longer than in Nubian. This is probably an effect attributable to differences in body size among breeds, since there is a trend toward increased gestation length from small to large breeds (GarcõÂa and Gall, 1981). The non-signi®cant effect of type of kidding on gestation length found in the present study is in agreement with that found by Chawla and Bhatnagar (1984) and Gangwar and Yadav (1987); however, Montaldo et al. (1987) reported that gestation of single (152 days) and twin births (151 days) were longer than that of triplet birth (149 days). 4. General discussion The main reason to import Alpine and Nubian goats into Venezuela was to increase milk production. Steinbach (1987) pointed out the need to evaluate imported breeds for their productive potential in the new environment and under management levels which are economically feasible, and added that `the performance of high-yielding exotic breeds is likely to suffer, to a variable degree, in a new, more stressful environment'. Kidding interval and proli®cacy (except the last 2 years) deteriorated as years progressed. From crosses of Alpine, Nubian and Toggenburg goats with Criollos, GarcõÂa et al. (1977) reported that the reproductive
performance of these European breeds was generally reduced in dry tropical areas because of the environmental stress and, more importantly, inadequate nutrition. In this study, feeding and health management was considered to be appropriate, thus, the possibility of a nutritional stress is unlikely. Therefore, it is possible that stressful forces that affected this herd were due mainly to climatic or management factors. Acknowledgements Torres-HernaÂndez would like to thank the National Fund for Agricultural Research of Venezuela for the scholarship granted. He also would like to thank the research team at the CIAE-Lara for their invaluable help and constant support. References Ali, A.K.A., Mohammad, W.A., Grossman, M., Shanks, R.D., Wiggans, G.R., 1983. Relationships among lactation and reproduction traits of dairy goats. J. Dairy Sci. 66, 1926±1936. Cabello, F.E., Andrade, M., Olmos, V.J., 1992. La productividad de la cabra de raza Nubia mantenida en clima semiaÂrido y sistema semi-intensivo (The productivity of the Nubian goat maintained in semiarid climate and semi-intensive system). Memorias de la VII ReunioÂn Nacional de Caprinocultura, Oaxaca, Oax. MeÂxico, pp. 132±142. Chawla, D.S., Bhatnagar, D.S., 1984. Reproductive performance of Alpine and Saanen does under intensive management. Ind. J. Anim. Sci. 54, 789±792. Dickson, L., GarcõÂa, O., 1991. SituacioÂn actual de la ganaderõÂa caprina y ovina en el estado Lara, Venezuela (Current situation of the caprine and ovine livestock in the state of Lara, Venezuela). Memoria de las Jornadas Nacionales de Ovinos y Caprinos. Maracaibo, Venezuela. Gangwar, S., Yadav, M.C., 1987. Factors affecting gestation length in Indian goats. Indian J. Dairy Sci. 40, 365±366. GarcõÂa, O., GarcõÂa, B. E., AranguÂ, M., Camacaro, A., 1977. Symposium on Goat Breeding in Mediterranean Countries, Malaga-Grenade-Murcia, Spain. EAAP and Spanish National Committee of Animal Production, Madrid, Spain, pp. 80±89. GarcõÂa, O., Gall, C., 1981. Goats in the dry tropics. In: Gall, C. (Ed.), Goat Production. Academic Press, New York, pp. 515± 551. Jan, I.A., Gupta, S.C., 1992. Performance of goats under intensive management system. Proceedings of the V International Conference on Goats, 2±8 March, New Delhi, India, pp. 550± 552. Montaldo, H., SaÂnchez, F., JuaÂrez, A., Forat, M., Rosales, J., 1987. A study of gestation length in ®ve breeds of goats. Proceedings of the IV International Conference on Goats, 8±13 March, Brasilia, Brazil, 1326 pp.
L. Dickson-Urdaneta et al. / Small Ruminant Research 36 (2000) 91±95 Mourad, M., 1993. Reproductive performance of Alpine and Zaraibi goats and growth of their ®rst cross in Egypt. Small Ruminant Res. 12, 379±384. Odubote, I.K., 1996. Genetic parameters for litter size at birth and kidding interval in the West African Dwarf Goats. Small Ruminant Res. 20, 261±265. Osuji, P.O., 1987. Intensive feeding systems for goats in Latin America and the Caribbean. Proceedings of the IV International Conference on Goats, 8±13 March, Brasilia, Brazil, pp. 1077± 1107. Sands, M.W., McDowell, R.E., 1978. The potential of the goat for milk production in the tropics. Cornell Int'l Mimeo. 60. Cornell University, Ithaca, NY, 53 pp. SAS, 1992. System for Linear Models, third ed. SAS Institute Inc., Cary, NC, USA, 329 pp. Silva, E., Galina, M.A., Palma, J.M., Valencia, J., 1998. Reproductive performance of Alpine dairy goats in a semiarid environment of Mexico under a continuous breeding system. Small Ruminant Res. 27, 79±84.
95
Steel, R.G.D., Torrie, J.H., 1980. Principles and Procedures of Statistics: A Biometrical Approach, 2nd ed. McGraw±Hill Publishing, New York. Steinbach, J., 1987. Evaluation of indigenous and exotic breeds and their crosses for production in unfavorable environments. Proceedings of the IV International Conference on Goats, 8± 13 March, Brasilia, Brazil, pp. 625±641. Terril, C.E., Foote, W.C., 1987. Estimating reproductive performance in goats. Proceedings of the IV International Conference on Goats, 8±13 March, Brasilia, Brazil, pp. 577±583. Wilson, R.T., Light, D., 1986. Livestock production in Central Mali: economic characters and productivity indices for traditionally managed goats and sheep. J. Anim. Sci. 62, 567±575. Wilson, R.T., Murayi, T., 1988. Productivity of the Small East African goat and its crosses with the Anglo-Nubian and the Alpine in Rwanda. Trop. Anim. Health Prod. 20, 219± 228.
Technical note
Comparison of Alpine and Nubian goats for some reproductive traits under dry tropical conditions L. Dickson-Urdanetaa, G. Torres-HernaÂndeza,*, C. Becerril-PeÂreza, F. GonzaÂlez-Cossioa, M. Osorio-Arcea, O. GarcõÂa-Betancourtb a
Colegio de Postgraduados, Montecillo, 56230, Mexico Fondo Nacional de Investigaciones Agropecuarias (FONAIAP), Ciae-Lara, Venezuela
b
Accepted 5 October 1999
Abstract The objective of this study was to compare some reproductive traits of Alpine and Nubian goats under an intensive management system in a dry tropical environment. Goats were kept under con®nement in half-covered pens and fed grass hay plus a commercial concentrate. Data were analyzed for kidding interval, proli®cacy and gestation length. No signi®cant (p > 0.05) breed effect was found for kidding interval; Alpine averaged 390.7 vs. 414.4 days for Nubian. There was, however, a signi®cant effect (p < 0.01) attributable to year of kidding; means ranged from 284 in 1989 to 590 days in 1994. Proli®cacy was signi®cantly affected (p < 0.01) by breed and year of kidding; Alpine and Nubians averaged 1.25 and 1.38 kids per parturition, respectively. Proli®cacy ranged from 1.53 in 1989 to 1.39 in 1994. A signi®cant (p < 0.01) breed effect on gestation length was found; means for Alpine and Nubians were 151.6 and 149.2 days, respectively. Kidding interval increased as years advanced, while proli®cacy decreased the ®rst 4 years of the study, thereafter began to increase. # 2000 Elsevier Science B.V. All rights reserved. Keywords: Goats; Reproductive ef®ciency; Intensive management; Climatic factors
1. Introduction In Venezuela there are 1.4 million goats raised mainly in arid and semiarid regions of the Lara, Zulia and Falcon States (Dickson and GarcõÂa, 1991). Most of the goats are raised under a prevailing extensive system, which involves limited feeding and sanitary practices and reproduction is never controlled. In early 1980s, a small group of farmers located in more * Corresponding author. Tel.: 595-20279; fax: 595-20279. E-mail address: [email protected] (G. Torres-HernaÂndez).
favorable areas of the country in term of feed supply decided to raise goats under more technical management conditions. To improve productive performance of native Criollo goats, farmers have used bucks of imported breeds such as Alpine, Nubian, Toggenburg, Saanen, and most recently Canarian, or to increase milk production and its by products have imported small herds of specialized dairy goats (mainly from USA). Kidding interval, proli®cacy and gestation length, among others, are traits in¯uenced by genetic, environmental, and management factors. They have eco-
0921-4488/00/$ ± see front matter # 2000 Elsevier Science B.V. All rights reserved. PII: S 0 9 2 1 - 4 4 8 8 ( 9 9 ) 0 0 1 3 0 - 3
92
L. Dickson-Urdaneta et al. / Small Ruminant Research 36 (2000) 91±95
nomic signi®cance since they determine reproductive performance (Terril and Foote, 1987) and the productivity of a goat enterprise. Accordingly, they might determine the preference of breeders for one breed over another within a production system. There is still limited information on reproductive performance of goats from temperate climate performing in the tropics (Chawla and Bhatnagar, 1984; Wilson and Murayi, 1988; Jan and Gupta, 1992; Mourad, 1993) and particularly in Venezuela. The present study was undertaken to estimate kidding interval, proli®cacy, and gestation length in a herd of Alpine and Nubian goats imported from the United States to Venezuela in 1988, and evaluate their reproductive performance when raised under intensive management. 2. Materials and methods 2.1. Animals and management Data for this study were collected from a goat herd founded initially with 133 does and their progeny maintained in facilities located at El CujõÂ State of Lara, northeast of Barquisimeto (108040 N and 698190 W). This region is a valley 420 m asl with average rainfall estimated at 586.9 mm and average temperature of 23.68C. The region is considered a very dry tropical forest. Data from 1988, the year of importation, were not included in the analysis since they were considered atypical. The herd was managed under intensive conditions. Goats were kept in six groups according to sex and physiological condition: (1) milking goats on; (2) dried and non-pregnant goats; (3) suckling kids; (4) goats in their last two months of gestation; (5) growing kids; and (6) bucks. Age of initial goats in the herd ranged from 1 to 2 years, and from 1990 on 15 yearling goats were incorporated each year to the breeding herd. Feeding consisted of a constant supply of Buffel (Cenchrus cilliaris) and Star grasses (Cynodon plectostachyus) given as hay. A high energy commercial concentrate ration with 17% CP was given at the rate of: 0.5 kg/day to open and growing females, 1 kg/day to does 2 months before parturition, 1.5 kg/day to milk producing does, 0.3 kg/day to bucks and ad libitum to suckling kids. A complete
mineral supplement and fresh water were always available. Osuji (1987) gave additional details on the feeding management. All goats were treated against internal parasites monthly, and were given dip baths against external parasites every 3 months. Goats were vaccinated against malignant edema, bacteridian carbon, hemorragic septicemia and tetanus. The reproductive management consisted of controlled mating after weaning. Does whose body weight exceeded 25.0 kg were exposed to males for the ®rst time. Bucks were kept in separate pens from females. Heat was detected using teaser bucks kept with the females year-round. Does in heat were exposed twice to a breeding buck selected according to breed and size. The following data were recorded: identi®cation of doe and buck, date of mating, weight of doe after parturition, sex and weight of kid, and date of kidding. Approximately, 10 different bucks were utilized every year. In 1989 and 1990, does were bred to 10 imported bucks; thereafter, bucks born and selected from the same herd were utilized, trying to avoid deliberate inbreeding. 2.2. Statistical analysis The General Linear Model procedures of the Statistical Analysis System were used (SAS, 1992). Data on kidding interval, proli®cacy, and gestation length were analyzed using a mixed model. Independent variables included in the model were breed of doe, doe nested within breed, year of kidding, season of kidding, type of kidding (except for proli®cacy) and the interaction between year of kidding and season of kidding. A preliminary analysis showed that the effect of age of doe was not signi®cant. Tukey's test was used to compare means (Steel and Torrie, 1980). 3. Results and discussion Differences between Alpine and Nubian were signi®cant for proli®cacy (p < 0.05) and gestation length (p < 0.01). Year of kidding had signi®cant effect on kidding interval (p < 0.05) and proli®cacy (p < 0.01). All other factors had non-signi®cant effects on the three traits studied.
L. Dickson-Urdaneta et al. / Small Ruminant Research 36 (2000) 91±95
93
Table 1 Least-squares means for kidding interval, proli®cacy and gestation length in a herd of Alpine and Nubian goats Trait
Kidding interval (day)
Prolificacy
Gestation length (day)
n
Mean
SE
n
Mean
SE
n
Mean
SE
120 66
390.7a 414.3a
15.3 21.5
178 94
1.25b 1.38a
0.04 0.05
151 79
151.6a 149.2a
0.27 0.33
23 59 42 24 18 20
284.4d 355.3c 370.1c 403.9b 411.4b 590.0a
36.6 25.3 26.6 36.5 43.3 70.6
31 78 66 39 28 30
1.53a 1.09d 1.32b 1.22c 1.33b 1.39b
0.11 0.06 0.06 0.09 0.11 0.13
30 71 56 29 20 24
150.8a 149.4a,b 149.9a 150.2a 149.3a,b 148.0b
0.64 0.46 0.43 0.59 0.76 0.70
Season of kidding Dry Rainy
74 112
407.5a 397.6a
24.8 19.2
108 164
1.34a 1.29a
0.05 0.05
100 130
149.1a 150.1a
0.35 0.35
Type of kidding Single Twin
109 77
396.2a 408.8a
18.7 22.9
± ±
± ±
± ±
152 78
149.9a 149.2a
0.30 0.44
Breed Alpine Nubian Year of kidding 1989 1990 1991 1992 1993 1994
a,b,c,d
Means within each class and in each column with different letters differ (p < 0.05).
3.1. Kidding interval Least-squares means for Alpine and Nubians were 390.7 and 414.3 days, respectively (Table 1). Lower values for this trait were found in the literature for both Alpine and Nubian breeds. Ali et al. (1983) reported 361 and 352 days, respectively, in the USA Chawla and Bhatnagar (1984) reported 364 days and Silva et al. (1998) reported 345 days for Alpine in India and Mexico, respectively. Whereas for Nubian, Jan and Gupta (1992) reported 337 days in India under intensive management. In Rwanda, Wilson and Murayi (1988) reported a kidding interval of 343 days in Small East African goats and its crosses with Anglo-Nubian and Alpine, and indicated that no signi®cant differences existed among these genotypes. GarcõÂa et al. (1977) mentioned that imported goats of European breeds have much longer kidding intervals (up to 100 more days). On the other hand, Sands and McDowell (1978) have indicated that European breeds performing in tropical conditions have kidding intervals very close to 1 year (345 days). Year of kidding had a signi®cant effect (p < 0.01) on kidding interval; least-squares means increased linearly from 284.4 days in 1989 to 411.4 in 1993 (Table 1). The sudden and unexpected increase observed in
1994 (590 days, cannot be reasonably explained other than the possibility of management and climate factors. Other authors have also found a signi®cant effect of year on kidding interval (Wilson and Light, 1986; Wilson and Murayi, 1988; Odubote, 1996). Generally, important changes in climatic conditions from one year to the next such as rainfall and temperature, as well as feeding and health practices, can be the main causes of year effect. 3.2. Proli®cacy Least-squares means for proli®cacy for Alpine and Nubian does were 1.25 and 1.38 kids/kidding, respectively (Table 1). A higher proli®cacy of Nubian does over that of Alpines (1.64 vs. 1.41) was also found by Jan and Gupta (1992) in India. Mourad (1993) reported an average of 1.45 for Alpine does, while Cabello et al. (1992) reported a value of 1.86 for Nubians. In Rwanda, Wilson and Murayi (1988) reported that differences in proli®cacy among SEA goat and its crosses with Anglo-Nubian and Alpine were not signi®cant (overall mean 1.75). Proli®cacy decreased from 1.53 in 1989 to 1.22 in 1992, and then increased to 1.33 in 1993 and 1.39 in 1994 (Table 1). Odubote (1996) found that litter size in
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L. Dickson-Urdaneta et al. / Small Ruminant Research 36 (2000) 91±95
West African Dwarf goats was signi®cantly affected (p < 0.05) by year of kidding. 3.3. Gestation length Gestation length was 151.6 for Alpine and 149.2 for Nubian does (p < 0.01). Chawla and Bhatnagar (1984) showed that the differences between Alpine and Saanen does in gestation length were not signi®cant. However, Gangwar and Yadav (1987) reported a signi®cant effect (p < 0.05) of breed on gestation length when comparing four breeds of goats in India (mean 145.1 days). Montaldo et al. (1987) also found a signi®cant breed effect (p < 0.05) on gestation length in Alpine, Nubian, Saanen, Toggenburg and Granadina goats under stall feeding in Mexico; in that study, Alpine does had a longer gestation length (152 days) than Nubians (151 days). Similar differences between Alpine and Nubian were reported by Ali et al. (1983). Jan and Gupta (1992) found that gestation length of Alpine (151 days) was one-day longer than in Nubian. This is probably an effect attributable to differences in body size among breeds, since there is a trend toward increased gestation length from small to large breeds (GarcõÂa and Gall, 1981). The non-signi®cant effect of type of kidding on gestation length found in the present study is in agreement with that found by Chawla and Bhatnagar (1984) and Gangwar and Yadav (1987); however, Montaldo et al. (1987) reported that gestation of single (152 days) and twin births (151 days) were longer than that of triplet birth (149 days). 4. General discussion The main reason to import Alpine and Nubian goats into Venezuela was to increase milk production. Steinbach (1987) pointed out the need to evaluate imported breeds for their productive potential in the new environment and under management levels which are economically feasible, and added that `the performance of high-yielding exotic breeds is likely to suffer, to a variable degree, in a new, more stressful environment'. Kidding interval and proli®cacy (except the last 2 years) deteriorated as years progressed. From crosses of Alpine, Nubian and Toggenburg goats with Criollos, GarcõÂa et al. (1977) reported that the reproductive
performance of these European breeds was generally reduced in dry tropical areas because of the environmental stress and, more importantly, inadequate nutrition. In this study, feeding and health management was considered to be appropriate, thus, the possibility of a nutritional stress is unlikely. Therefore, it is possible that stressful forces that affected this herd were due mainly to climatic or management factors. Acknowledgements Torres-HernaÂndez would like to thank the National Fund for Agricultural Research of Venezuela for the scholarship granted. He also would like to thank the research team at the CIAE-Lara for their invaluable help and constant support. References Ali, A.K.A., Mohammad, W.A., Grossman, M., Shanks, R.D., Wiggans, G.R., 1983. Relationships among lactation and reproduction traits of dairy goats. J. Dairy Sci. 66, 1926±1936. Cabello, F.E., Andrade, M., Olmos, V.J., 1992. La productividad de la cabra de raza Nubia mantenida en clima semiaÂrido y sistema semi-intensivo (The productivity of the Nubian goat maintained in semiarid climate and semi-intensive system). Memorias de la VII ReunioÂn Nacional de Caprinocultura, Oaxaca, Oax. MeÂxico, pp. 132±142. Chawla, D.S., Bhatnagar, D.S., 1984. Reproductive performance of Alpine and Saanen does under intensive management. Ind. J. Anim. Sci. 54, 789±792. Dickson, L., GarcõÂa, O., 1991. SituacioÂn actual de la ganaderõÂa caprina y ovina en el estado Lara, Venezuela (Current situation of the caprine and ovine livestock in the state of Lara, Venezuela). Memoria de las Jornadas Nacionales de Ovinos y Caprinos. Maracaibo, Venezuela. Gangwar, S., Yadav, M.C., 1987. Factors affecting gestation length in Indian goats. Indian J. Dairy Sci. 40, 365±366. GarcõÂa, O., GarcõÂa, B. E., AranguÂ, M., Camacaro, A., 1977. Symposium on Goat Breeding in Mediterranean Countries, Malaga-Grenade-Murcia, Spain. EAAP and Spanish National Committee of Animal Production, Madrid, Spain, pp. 80±89. GarcõÂa, O., Gall, C., 1981. Goats in the dry tropics. In: Gall, C. (Ed.), Goat Production. Academic Press, New York, pp. 515± 551. Jan, I.A., Gupta, S.C., 1992. Performance of goats under intensive management system. Proceedings of the V International Conference on Goats, 2±8 March, New Delhi, India, pp. 550± 552. Montaldo, H., SaÂnchez, F., JuaÂrez, A., Forat, M., Rosales, J., 1987. A study of gestation length in ®ve breeds of goats. Proceedings of the IV International Conference on Goats, 8±13 March, Brasilia, Brazil, 1326 pp.
L. Dickson-Urdaneta et al. / Small Ruminant Research 36 (2000) 91±95 Mourad, M., 1993. Reproductive performance of Alpine and Zaraibi goats and growth of their ®rst cross in Egypt. Small Ruminant Res. 12, 379±384. Odubote, I.K., 1996. Genetic parameters for litter size at birth and kidding interval in the West African Dwarf Goats. Small Ruminant Res. 20, 261±265. Osuji, P.O., 1987. Intensive feeding systems for goats in Latin America and the Caribbean. Proceedings of the IV International Conference on Goats, 8±13 March, Brasilia, Brazil, pp. 1077± 1107. Sands, M.W., McDowell, R.E., 1978. The potential of the goat for milk production in the tropics. Cornell Int'l Mimeo. 60. Cornell University, Ithaca, NY, 53 pp. SAS, 1992. System for Linear Models, third ed. SAS Institute Inc., Cary, NC, USA, 329 pp. Silva, E., Galina, M.A., Palma, J.M., Valencia, J., 1998. Reproductive performance of Alpine dairy goats in a semiarid environment of Mexico under a continuous breeding system. Small Ruminant Res. 27, 79±84.
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Steel, R.G.D., Torrie, J.H., 1980. Principles and Procedures of Statistics: A Biometrical Approach, 2nd ed. McGraw±Hill Publishing, New York. Steinbach, J., 1987. Evaluation of indigenous and exotic breeds and their crosses for production in unfavorable environments. Proceedings of the IV International Conference on Goats, 8± 13 March, Brasilia, Brazil, pp. 625±641. Terril, C.E., Foote, W.C., 1987. Estimating reproductive performance in goats. Proceedings of the IV International Conference on Goats, 8±13 March, Brasilia, Brazil, pp. 577±583. Wilson, R.T., Light, D., 1986. Livestock production in Central Mali: economic characters and productivity indices for traditionally managed goats and sheep. J. Anim. Sci. 62, 567±575. Wilson, R.T., Murayi, T., 1988. Productivity of the Small East African goat and its crosses with the Anglo-Nubian and the Alpine in Rwanda. Trop. Anim. Health Prod. 20, 219± 228.