Journal of Dairy Science
Volume 93, Issue 1 , Pages 370-372, January 2010

Short communication: Genetic and environmental relationships between milk yield and kidding interval in dairy goats

  • H.H. Montaldo

      Affiliations

    • Departamento de Genética y Bioestadística, Facultad de Medicina Veterinaria y Zootecnia, Universidad Nacional Autónoma de México, Ciudad Universitaria, D.F. 04510, Mexico
    • Corresponding Author InformationCorresponding author.
    • ,
  • M. Valencia-Posadas

      Affiliations

    • División de Ciencias de la Vida, Campus Irapuato-Salamanca, Universidad de Guanajuato, ExHacienda El Copal, Irapuato, Guanajuato 36500, Mexico
    • ,
  • G.R. Wiggans

      Affiliations

    • Animal Improvement Programs Laboratory, Agricultural Research Service, USDA, Beltsville, MD 20705-2350
    • ,
  • L. Shepard

      Affiliations

    • American Dairy Goat Association, Spindale, NC 28160
    • ,
  • J.A. Torres-Vázquez

      Affiliations

    • Centro Nacional de Investigación en Fisiología y Mejoramiento Animal, Instituto Nacional de Investigaciones Forestales, Agrícolas y Pecuarias, Secretaría de Agricultura, Ganadería, Desarrollo Rural, Pesca y Alimentación, Ajuchitlán, Querétaro 76280, Mexico

Received 27 July 2009; accepted 30 September 2009.

Article Outline

Abstract 

First-parity 305-d milk yield and intervals between first and second kiddings from 1975 through 2005 were analyzed to estimate genetic and environmental parameters for United States Alpine, LaMancha, Nubian, Saanen, and Toggenburg dairy goats. The data set included 43,612 does with first-parity milk yield and 25,863 does with first kidding interval. Parameters were estimated by REML using bivariate mixed models within and across breeds. Fixed effects were month and herd-year of kidding within breed and month and breed-herd-year of kidding across breeds. Random effects were animal and residual. The heritability estimate for first-parity milk yield was 0.36±0.01 across breeds and ranged from 0.35 to 0.38 within breed; heritability for first kidding interval was 0.05±0.01 across breeds and ranged from 0.00 to 0.15 within breed. The estimate of the genetic correlation between first-parity milk yield and first kidding interval was positive (unfavorable) across breeds (0.35±0.09). Estimates of environmental correlations within and across breeds were positive (0.16–0.25). The presence of unfavorable genetic relationships between milk yield and kidding interval indicates a need to include reproductive performance as a selection criterion.

Key words: genetic parameter, kidding interval, milk yield, dairy goat

 

Several studies (e.g., Pryce et al., 2004, Andersen-Ranberg et al., 2005) have indicated unfavorable genetic and environmental correlations between milk yield and fertility in dairy cattle. Because of the economic importance of fertility, reproduction traits have been incorporated as a selection criterion for dairy cattle in many countries (e.g., VanRaden, 2004). Knowledge of those relationships in dairy goats is limited. Estimates of heritabilities and correlations are needed (Montaldo and Manfredi, 2002). The objective of this study was to estimate heritabilities of milk yield and kidding interval for 5 goat breeds based on first kiddings as well as genetic, environmental, and phenotypic correlations between those traits.

Milk yield and kidding interval data from DHI lactation records in the USDA national dairy database (Beltsville, MD) and provided to the American Dairy Goat Association (Spindale, NC) were analyzed for kiddings between 1975 and 2005. Pedigree information was available for all does with records and their ancestors for animals born in 1971 or later. First-parity, mature-equivalent, 305-d milk yield (Wiggans and Hubbard, 2001), and interval between first and second kiddings were analyzed. Only data from lactations with ≥100 DIM and from herd-year-breed combinations and sires with ≥2 daughter records were retained for final analysis. Records with first kidding intervals of <170 or >730 d were considered to be abnormal and were excluded. Numbers of sires and does for first-parity milk yield and first kidding interval are shown in Table 1 along with means (unadjusted) and phenotypic SD (unadjusted and from the analysis).

Table 1. Numbers of sires and does, means (unadjusted), and phenotypic SD (unadjusted and from model analysis) for first-parity milk yield and interval between first and second kiddings of United States dairy goats by breed
ItemAlpineLaManchaNubianSaanenToggenburgAll breeds
Sires, n2,3469942,5441,1231,0368,043
First-parity milk yield
Does, n15,1474,63312,2275,8285,77743,612
Mean, kg1,0909789281,1871,0501,040
Phenotypic SD, kg
Unadjusted322290303392317379
From model analysis245216210278235237
First kidding interval
Does, n9,2222,6237,0753,4513,49225,863
Mean, d381374373384382379
Phenotypic SD, d
Unadjusted899087938989
From model analysis828275777879

Data were analyzed within breed (Alpine, LaMancha, Nubian, Saanen, and Toggenburg) with bivariate mixed models that included fixed effects for month and herd-year of kidding. Random effects were animal (with all relationships considered through the inverse of the numerator relationship matrix) and residual. Covariance components were estimated with ASReml (Gilmour et al., 2006). All breeds also were analyzed together by including a breed-herd-year instead of herd-year effect in the model.

Heritability estimates for first-parity milk yield (Table 2) were large (0.35– 0.38) compared with previous estimates (Montaldo and Manfredi, 2002; Valencia et al., 2007; Torres-Vázquez et al., 2009), which shows the possibility for increased accuracy of selection and more rapid genetic improvement for productivity (Montaldo et al., 1994). The heritability estimate for first-parity milk yield from the analysis across breeds was 0.36±0.01.

Table 2. Estimates of heritability and genetic, environmental, and phenotypic correlations for first-parity milk yield and interval between first and second kiddings of United States dairy goats by breed
ParameterAlpineLaManchaNubianSaanenToggenburgAll breeds
Heritability
First-parity milk yield0.36±0.020.38±0.050.38±0.020.35±0.040.36±0.040.36±0.01
First kidding interval0.06±0.020.15±0.060.000.07±0.050.02±0.040.05±0.01
Genetic correlation0.31±0.120.36±0.17—0.26±0.210.38±0.400.35±0.09
Environmental correlation0.22±0.020.21±0.030.21±0.020.16±0.040.25±0.040.20±0.01
Phenotypic correlation
From model analysis0.21±0.010.22±0.020.21±0.020.17±0.020.23±0.020.20±0.01
Unadjusted0.170.140.150.100.150.151

1Weighted mean across breeds.

Heritability estimates for first kidding interval (Table 2) ranged from 0.00 to 0.15. The heritability estimate of 0.00 for Nubians may be the result of sampling error; larger data sets may be needed to estimate genetic parameters accurately for first kidding interval. The across-breed heritability estimate for first kidding interval was 0.05±0.01, which was slightly larger than the estimates of 0.02 for Polish goats and 0.03 for Norwegian goats reported by Bagnicka et al. (2007). Breed variation in heritability estimates for first kidding interval may be caused by low heritability for all breeds and large sampling variances, as shown by the relatively large standard errors (Table 2). Previous heritability estimates for kidding interval from small samples (Odubote, 1996; Ribeiro et al., 2000; Lôbo and da Silva, 2005) probably had large standard errors; however, those estimates ranged from 0.01 to 0.09, which indicated that heritability is less than 0.10.

Estimates of genetic correlation between first-parity milk yield and first kidding interval (Table 2) were positive (unfavorable) for Alpines (0.31), LaManchas (0.36), Saanens (0.26), and Toggenburgs (0.38). A likelihood ratio test (Gilmour et al., 2006) indicated that the genetic correlation was different from zero for Alpines (P<0.01) and LaManchas (P<0.05) but not for Saanens or Toggenburgs (P>0.05). The genetic correlation was not estimable for Nubians because the heritability estimate for first kidding interval was near zero. The across-breed genetic correlation (0.35) based on data from all breeds also was different from zero (P<0.01). The low heritability estimates for first kidding interval compared with first-parity milk yield and positive genetic correlations between first kidding interval and first-parity milk yield agree with reports for reproductive traits of dairy cattle (Castillo-Juarez et al., 2000, Pryce et al., 2004, Andersen-Ranberg et al., 2005). VanRaden et al. (2004) estimated the genetic correlation between days open and milk yield to be 0.38 for United States Holsteins. Because of the positive genetic correlation between first-parity milk yield and first kidding interval, selection indexes should include first kidding interval to prevent a decline in fertility.

Estimates of the environmental correlations between first-parity milk yield and first kidding interval (Table 2) were positive (unfavorable) for all breeds (0.16–0.25), with small standard errors. The across-breed environmental correlation was 0.20. Because of the small heritability estimates for first kidding interval, phenotypic correlations (Table 2) were determined almost completely by environmental correlations. Similar estimates have been reported for dairy cattle (Pryce et al., 2004, Andersen-Ranberg et al., 2005, Mackey et al., 2007). Unadjusted phenotypic correlations between milk yield and kidding interval, which include the covariances across herd-years (Table 2), were also positive, but they were smaller than phenotypic correlations from model residuals. The environmental correlations indicate some environmental antagonism between milk yield and fertility within herd-year. However, the unadjusted phenotypic correlations, which include herd-year effects, were smaller than environmental correlations, indicating favorable management effects across herd-years for both traits.

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Acknowledgments 

The authors thank S. M. Hubbard (Animal Improvement Programs Laboratory, Agricultural Research Service, USDA, Beltsville, MD) for suggestions on manuscript improvement.

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References 

  1. Andersen-Ranberg IM, Klemetsdal G, Heringstad B, Steine T. Heritabilities, genetic correlations, and genetic change for female fertility and protein yield in Norwegian dairy cattle. J. Dairy Sci. 2005;88:348–355
  2. Bagnicka E, Wallin E, Łukaszewicz M, Ǻdnøy T. Heritability for reproduction traits in Polish and Norwegian populations of dairy goat. Small Rumin. Res. 2007;68:256–262
  3. Castillo-Juarez H, Oltenacu PA, Blake RW, McCulloch CE, Cienfuegos-Rivas EG. Effect of herd environment on the genetic and phenotypic relationships among milk yield, conception rate, and somatic cell score in Holstein cattle. J. Dairy Sci. 2000;83:807–814
  4. Gilmour AR, Cullis BR, Welham SJ, Thompson R. ASReml User Guide. Hemel Hempstead, UK: Release 2.0. VSN International Ltd.; 2006;
  5. Lôbo RNB, da Silva FLR. Parâmetros genéticos para características de interesse econômico em cabras das raças Saanen e Anglo-nubiana. [Genetic parameters for economics traits in Saanen and Anglo-Nubian goats.]. Revista Ciência Agronômica. 2005;36:104–110
  6. Mackey DR, Gordon AW, McCoy MA, Verner M, Mayne CS. Associations between genetic merit for milk production and animal parameters and the fertility performance of dairy cows. Animal. 2007;1:29–43
  7. Montaldo, H. H., and E. Manfredi. 2002. Organisation of selection programmes for dairy goats. Commun. no. 01–35 in Proc. 7th World Congr. Genet. Appl. Livest. Prod., Montpellier, France. INRA, Paris, France.
  8. Montaldo HH, Valencia-Posadas M, Sánchez F. Respuesta esperada a la selección para producción de leche en caprinos con pruebas de progenie, MOET y selección masal. [Expected genetic response for milk production in goats with progeny testing, MOET and mass selection.]. Arch. Zootec. 1994;43:335–343
  9. Odubote IK. Genetic parameters for litter size at birth and kidding interval in the West African Dwarf goats. Small Rumin. Res. 1996;20:261–265
  10. Pryce JE, Royal MD, Garnsworthy PC, Mao IL. Fertility in the high-producing dairy cow. Livest. Prod. Sci. 2004;86:125–135
  11. Ribeiro AC, Lui JF, Queiroz SA, Ribeiro SDA, Resende KT. Genetic and environmental effects on the age at first kidding and kidding interval in a Saanen goat herd. Ars Vet. 2000;16:192–197
  12. Torres-Vázquez JA, Valencia-Posadas M, Castillo-Juárez H, Montaldo HH. Genetic and phenotypic parameters of milk yield, milk composition and age at first kidding in Saanen goats from Mexico. Livest. Sci. 2009;126:147–153
  13. Valencia M, Dobler J, Montaldo HH. Genetic and phenotypic parameters for lactation traits in a flock of Saanen goats in Mexico. Small Rumin. Res. 2007;68:318–322
  14. VanRaden PM. Invited review: Selection on net merit to improve lifetime profit. J. Dairy Sci. 2004;87:3125–3131
  15. VanRaden PM, Sanders AH, Tooker ME, Miller RH, Norman HD, Kuhn MT, et al. Development of a national genetic evaluation for cow fertility. J. Dairy Sci. 2004;87:2285–2292
  16. Wiggans GR, Hubbard SM. Genetic evaluation of yield and type traits of dairy goats in the United States. J. Dairy Sci. 2001;84(E-Suppl):E69–E73

PII: S0022-0302(10)70296-4

doi:10.3168/jds.2009-2593

Journal of Dairy Science
Volume 93, Issue 1 , Pages 370-372, January 2010

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