M. S. Dhanoa

Biohydrogenation and digestion of long chain fatty acids in steers fed on different sources of lipid

Scollan, N. D., Dhanoa, M. S., Choi, N.-J., Maeng, W. J., Enser, M., Wood, J. D. (2001). Biohydrogenation and digestion of long chain fatty acids in steers fed on different sources of lipid. Journal of Agricultural Science, 136, (3), 345-355

Effect of genotype of Trifolium repens on mycorrhizal symbiosis with Glomus mosseae

Eason, W. R., Webb, K. J., Michaelson-Yeates, T. P. T., Abberton, M. T., Griffith, G. W., Culshaw, C. M., Hooker, J. E., Dhanoa, M. S. (2001). Effect of genotype of Trifolium repens on mycorrhizal symbiosis with Glomus mosseae. Journal of Agricultural Science, 137 (1), 27-36. Sponsorship: BBSRC

Protein supplementation of grass silages of differing digestibility for growing steers

Scollan, N. D., Sargeant, A., McAllan, A. B., Dhanoa, M. S. (2001). Protein supplementation of grass silages of differing digestibility for growing steers. Journal of Agricultural Science, 136, 89-98. Sponsorship: MAFF

Evaluation of a mechanistic lactation model using cow, goat and sheep data

A mechanistic lactation model, based on a theory of mammary cell proliferation and cell death, was studied and compared to the equation of Wood (1967). Lactation curves of British Holstein Friesian cows (176 curves), Spanish Churra sheep (40 curves) and Spanish Murciano–Granadina goats (30 curves) were used for model evaluation. Both models were fitted in their original form using non-linear least squares estimation. The parameters were compared among species and among parity groups within species. In general, both models provided highly significant fits to lactation data and described the data accurately. The mechanistic model performed well against Woods 1967 equation (hereafter referred to as Woods equation), resulting in smaller residual mean square values in more than two-thirds of the datasets investigated, and producing parameter estimates that allowed appropriate comparisons and noticeable trends attributed to shape. Using Akaike or Bayesian information criteria, goodness-of-fit with the mechanistic model was superior to that with Woods equation for the cow lactation curves, with no significant differences between models when fitted to goat or sheep lactation curves. The rate parameters of the mechanistic model, representing specific proliferation rate of mammary secretory cells at parturition, decay associated with reduction in cell proliferation capacity with time and specific death rate of mammary secretory cells, were smaller for primiparous than for multiparous cows. Greater lactation persistency of cows compared to goats and sheep, and decrease in persistency with parity, were shown to be represented by different values of the specific secretory cell death rate parameter in the mechanistic model. The plausible biological interpretation and fitting properties of the mechanistic model enable it to be used in complex models of whole-cow digestion and metabolism and as a tool in selection programmes and by dairy producers for management decisions.

Effects of diet and stage of development on partitioning of nutrients between fat and lean deposition in steers

Scollan, N. D., Dhanoa, M. S., Kim, E. J., Dawson, J. M., Buttery, P. J. (2003). Effects of diet and stage of development on partitioning of nutrients between fat and lean deposition in steers. Animal Science, 76, (2), 237-249.

Effects of supplementary concentrates on growth and partitioning of nutrients between different body components in steers fed on grass silage at similar levels of metabolizable energy intake

Kim, E. J., Scollan, N. D., Dhanoa, M. S., Buttery, P. J. (2003). Effects of supplementary concentrates on growth and partitioning of nutrients between different body components in steers fed on grass silage at similar levels of metabolisable energy intake. Journal of Agricultural Science, 141, 103-112. Sponsorship: DEFRA

Simplified estimation of forage degradability in the rumen assuming zero-order degradation kinetics

In the present paper, a simplified procedure using few in situ data points is derived and then evaluated (using a large database) against reference values estimated with the standard nylon bag first-order kinetics model. The procedure proposed involved a two-stage mathematical process, with a statistical prediction of some degradation parameters (such as lag time) and then a kinetic model derived by assuming degradation follows zero-order kinetics to determine effective degradability in the rumen (E). In addition to the estimation of washout fraction and discrete lag, which is common to both procedures, the simplified procedure requires measurement of dry matter losses at one incubation time point only. Thus, interference of the animal rumen will be much reduced, which will lead to increased capacity for feed evaluation. Calibration of the zero-order model against the first-order model showed that suitable estimates of E can be obtained with disappearance at 24, 48 or 72 h as the single incubation end time point. The strength of the calibration is such that an end incubation time point as low as 24 h may be sufficient, which may reduce substantially the total incubation time required and thus the impact on the experimental animal. Relevant regression equations to predict reference values of parameters such as lag time or E are also developed and validated.

Fish-meal supplementation of grass silage offered to young steers: Effects on growth, body composition and nutrient efficiency

Sanderson, R., Dhanoa, M. S., Thomas, C., McAllan, A. B. (2001). Fish-meal supplementation of grass silage offered to young steers: effects on growth, body composition and nutrient efficiency. Journal of Agricultural Science, 137, (1), 85-96. Sponsorship: Eastman Kodak (Animal Division)

Comment on “The structural relationship: regression in biology”

Supplementary information relevant to structural relationship regression in biology as discussed by McArdle (1988; Can. J. Zool. 66(11): 2329–2339) is presented. Although McArdle presented both linear and multiple linear regression models, we limit our comment to the linear model only. McArdle’s eq.xa02 is corrected. Deming’s alternative form of the maximum likelihood (ML) solution (Deming 1943; Statistical adjustment of data. John Wiley and Sons, Inc., New York) is introduced. In the ML solution, the ratio of the mean measurement variances of the yxa0and xxa0variables is assumed constant over the range of the data. However, when λML is not constant, then iteratively reweighted generalized Deming regression or functional relationship estimation by maximum likelihood is more appropriate.

Estimating maintenance energy using type I and type II regression models.

2 paginas, 1 tabla.-- Trabajo presentado al 3rd EAAP International Symposium on Energy and Protein Metabolism (Parma, Italia, 6 al 10 de Septiembre, 2010).--EAAP Publication No. 1272 paginas, 1 tabla.-- Trabajo presentado al 3rd EAAP International Symposium on Energy and Protein Metabolism (Parma, Italia, 6 al 10 de Septiembre, 2010).--EAAP Publication No. 127