Skip to main content
×
×
Home

A comparison among equations to characterize lactation curves in beef cows

  • W. D. Hohenboken (a1), A. Dudley (a1) and D. E. Moody (a1)
Abstract

Monthly and fortnightly milk production records were analysed from 59 autumn-calving Angus and Angus × Holstein crossbred cows. Half the cows had been administered 10 mg thyroxine per day from day 60 to 120 of lactation and half were controls. Four published equations to characterize individual lactation curves were compared. These were: (1) log Y(n) = log –a1 + b1log n – c1n (Wood); (2) equation 1 with each log Y(n)2 weighted by Yin)2 (Wood weighted); (3) log [Y(n)/n7 = log l/a3 – k3n(Jenkins); and (4) log Y(n) = a4 – b4n‘(l + 25·5 n’) + c4n2 = d 4/ n (Morant), where Y(n) is milk yield on day n of lactation, n' is n–110 (the mid point of lactation), and the a, b, c, k and d parameters are estimated from solution of the equations. The lactation curve from the Jenkins equation projected peak milk yield to occur some 30 days later than estimates from the other equations. It underestimated production early and late in lactation and overestimated it during mid lactation. For several cows, the Morant equation projected that peak production occurred at the end of lactation. Also, analysis of variance of milk production variables was less sensitive when the traits were estimated by the Morant equation than when they were estimated by one of the others. The Wood weighted equation resulted in estimates of peak day of lactation and peak yield that were less variable and more realistic than estimates from the Wood equation. Collectively, therefore, the Wood weighted equation was deemed most suitable to characterize variability among and within these beef cows in milk production. All four equations, however, ranked the 59 cows similarly for estimated 220-day yield.

Copyright
References
Hide All
Clutter, A. C. and Nielsen, M. K. 1987. Effect of level of beef cow milk production on pre- and postweaning calf growth. Journal of Animal Science 64: 13131322.
Cobby, J. M. and Le Du, Y. L. P. 1978. On fitting curves to lactation data. Animal Production 26:127133.
Jenkins, T. G. and Ferrell, C. L. 1984. A note on lactation curves of crossbred cows. Animal Production 39: 479482.
Lubritz, D. L., Forrest, K. and Robison, O. W. 1989. Age of cow and age of dam effects on milk production of Hereford cows. Journal of Animal Science 67: 25442549.
Montaño-Bermudez, M. and Nielsen, M. K. 1990. Biological efficiency to weaning and to slaughter of crossbred beef cattle with different genetic potential for milk. Journal of Animal Science 68: 22972309.
Moody, D. E., Hohenboken, W. D., Beal, W. E. and Thye, F. W. 1992. Concentration of plasma cholesterol in beef cows and calves, milk production and calf gain. Journal of Animal Science 70: In Press.
Morant, S. V. and Gnanasakthy, A. 1989. A new approach to the mathematical formulation of lactation curves. Animal Production 49:151162.
Rowlands, G. J., Lucey, S. and Russell, A. M. 1982. A comparison of different models of the lactation curve in dairy cattle. Animal Production 35:135144.
Statistical Analysis Systems Institute. 1985. SAS user's guide: statistics. SAS Institute Inc., Cary, NC.
Wood, P. D. P. 1967. Algebraic model of the lactation curve in cattle. Nature, London 216:164165.
Recommend this journal

Email your librarian or administrator to recommend adding this journal to your organisation's collection.

Animal Science
  • ISSN: 1357-7298
  • EISSN: 1748-748X
  • URL: /core/journals/animal-science
Please enter your name
Please enter a valid email address
Who would you like to send this to? *
×

Keywords

Metrics

Full text views

Total number of HTML views: 0
Total number of PDF views: 0 *
Loading metrics...

Abstract views

Total abstract views: 0 *
Loading metrics...

* Views captured on Cambridge Core between <date>. This data will be updated every 24 hours.

Usage data cannot currently be displayed