An Optimum Regression Model to Estimate Economic Values for Milk Yield, Milk Yield Persistency and Calving Interval in Dairy Cattle

محورهای موضوعی : Camel

S. Falahpour ¹ (Department of Animal Science, Faculty of Agriculture, University of Guilan, Rasht, Iran)
A.A. Shadparvar ² (Department of Animal Science, Faculty of Agriculture, University of Guilan, Rasht, Iran)
N. Ghavi Hossein Zadeh ³ (Department of Animal Science, Faculty of Agriculture, University of Guilan, Rasht, Iran)
M. Mehdi Zadeh Stalkh Kohi ⁴ (Agriculture Jihad Organization of Guilan, Guilan, Rasht, Iran)

تاریخ دریافت : 1390/12/12 تاریخ پذیرش : 1391/04/16 تاریخ انتشار : 1392/03/11

کلید واژه: Economic value, milk yield, calving interval, milk yield persistency, Regression model,

چکیده مقاله :

Emphasis on milk yield (MY) as well as milk yield persistency (MYP) and calving interval (CI) is necessary to achieve more sustainable productionin dairy cattle. Therefore the main objective of this study was to find an optimum regression model to estimate economic values for MY, MYP and CI.Using a deterministic bio-economic model, seventyfiveproduction states differing mainly in MY, MYPand CIwere studied.For each production state, the total revenue comprised income from sold milk, calves of one week of age and manure. Feed costs were obtained from energy requirements for maintenance, growth, lactation and pregnancy. Non feed costs included costs of net replacement, health, artificial insemination and some others which were modeled as a function of CI.Multiple regression analyses of annual profits for production state on the means of MY, MYP and CI were used to estimate the economic values. Two different regression models were used. Both models included the linear effect of MY and the quadratic effect of MYP. However, in one model the effect of CI was linear (Model CIL) whilst it wasquadratic in the other (Model CIQ). Under both models, economic value for MY was positive (0.10 $ for model CIL and 0.32 $ for model CIQ) as was expected for the assumed milk pricing system. Economic values for MYP in the models had different signs (-118.2 $ for model CIL and 715.55 $ for model CIQ). Under model CIQ maximum profit was associated with a value of MYP greater than unity and was not consistent with the definition of persistency. Economic value of CI was negative under both models (-2.68 $ for model CIL and -6.36 for model CIQ). In the model CIQ, the profit function had a minimum value for CI (at 803 days) which was not consistent with the previously reported relationship between profit and CI. Estimates of economic values for MY,MYP and CIshowed that the model CIL was superior to the model CIQ due to a lower number of fitted effects and increased consistency with the real situation of dairy systems.

منابع و مأخذ:

Amer P.R., Mpofu N. and Bondoc O. (1998). Definition of breeding objectives for sustainable production systems. Pp. 97-104 in Proc. 6^th World Cong. Genet. Appl. Livest. Prod. Armidale, NSW, Australia.
Appuhamy J.A.D.R.N., Cassell B.G., Dechow C.D. and Cole J.B. (2007). Phenotypic relationships of common health disorders in dairy cows to lactation persistency estimated from daily milk weights. J. Dairy Sci. 90, 4424-4434.
Arbel R., Bigun Y., Ezra E., Sturman H. and Hojman D. (2001). The effect of extended calving intervals in high-yielding cows on milk production and profitability. J. Dairy Sci. 84, 600-608.
Cole J.B. and Null D.J. (2009).Genetic evaluation of lactation persistency for five breeds of dairy cattle.J. Dairy Sci. 92, 2248-2258.
Dekkers J.C.M. (1991). Estimation of economic values for dairy cattle breeding goals-Bias due to sub-optimal management policies. Livest. Prod. Sci. 29, 131-149.
Dekkers J.C.M., Ten Hag J.H. and Weersink A. (1998). Economic aspects of persistency of lactation in dairy cattle.Livest. Prod. Sci. 53, 237-252.
Ghavi Hossein-Zadeh N., Nejati-Javaremi A., Miraei-Ashtiani S.R., Kohram H. and Honarvar M. (2011). Bio-economic model to evaluate twinning rate using sexed embryo transfer in dairy herds. Animal. 5, 1705-1719.
González-Recio O., Pérez-Cabal M.A. and Alenda R. (2004). Economic value of female fertility and its relationship with profit Spanish dairy cattle. J. Dairy Sci. 87, 3053-3061.
Groen A.F. (1989). Economic values in cattle breeding. I. Influences of production circumstances in situations without output limitations. Livest. Prod. Sci. 22, 1-16.
Hazel L.N. (1943). The genetic basis for constructing selection indexes.Genetics. 28, 476-490.
Hosseinpour Mashhadi M., Emam Jomeh Kashan N., Nassiry M.R. and VaezTorshizi R. (2008). Prediction breeding value and genetic parameter in Iranian Holstein bulls for milk production traits. Pakistan J. Biol. Sci. 11, 108-112.
Kahi A.K. and Nitter G. (2004). Developing breeding schemes for pasture based dairy production systems in Kenya. I. Derivation of economic values using profit functions. Livest. Prod. Sci. 88, 161-177.
Korver S., Van Arendonk J.A.M. and Koops W.J. (1985). A function for live-weight change between two calvings in dairy cattle. Anim. Prod. 40, 233-241.
Muir B.L., Fatehi J. and Schaeffer L.R. (2004). Genetic relationships between persistency and reproductive performance in first-lactation Canadian Holsteins. J. Dairy Sci. 87, 3029-3037.
NRC. (2001). Nutrient Requirements of Dairy Cattle. 7^th Ed. National Academy Press, Washington, DC, USA.
Nebel R.L. and McGilliard M.L. (1993). Interactions of high milk yield and reproductive performance in dairy cows. J. Dairy Sci. 76, 3257-3268.
Olesen I., Groen A.F. and Gjerde B. (2000). Definition of animal breeding goals for sustainable production systems. J. Anim. Sci. 78, 570-582.
Ponzoni R.W. (1992). Genetic Improvement of Hair Sheep in the Tropics. Food. Agric. Org. United National, Rome, Italy.
Sadeghi-Sefidmazgi A., Moradi-Shahrbabak M., Nejati-Javaremi A., Miraei-Ashtiani S.R. and Amer P.R. (2012).Breeding objectives for Holstein dairy cattle in Iran.J. Dairy Sci. 95, 3406-3418.
Sadeghi-Sefidmazgi A., Moradi-Shahrbabak M., Nejati-Javaremi A. and Shadparvar A.A. (2009). Estimation of economic values in three breeding perspectives for longevity and milk production traits in Holstein dairy cattle in Iran. Italian J. Anim. Sci. 8, 359-375.
Shadparvar A.A. and Nikbin S. (2008). Optimum model for analyzing lifetime profitability of Holstein cows. Asian-australas. J. Anim. Sci. 21, 769-775.
Sölkner J. and Fuchs W. (1987). A comparison of different measures of persistency with special respect to variation of test-day milk yields. Livest. Prod. Sci. 16, 305-319.
Togashi K. and Lin C.Y. (2009). Economic weights for genetic improvement of lactation persistency and milk yield. J. Dairy Sci. 92, 2915-2921.
Van Arendonk J.A.M. and Dijkhuizen A.A. (1985). Studies on the replacement policies in dairy catlle: III. Influence of variation in reproduction and production. Livest. Prod. Sci. 13, 333-349.
Wolfová M., Wolf J., Kvapilík J. and Kica J. (2007).Selection for profit in cattle:I. Economic weights for purebred dairy cattle in the Czech Republic. J. Dairy Sci. 90, 2442-2455.
Wood P.D.P. (1967). Algebraicmodel of the lactation curve in cattle. Nature. 216, 164-165.