Milk Production Functions Incorporating Variables for Cow Characteristics and Environment

Heady, Earl O.; Jacobson, N. L.; Freeman, A.E.; Madden, J. Patrick

doi:10.2307/1236469

Cited by 15 publications

(12 citation statements)

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“…Confidence regions for annual optima would be of interest here and could be derived. See Heady, Jacobson, Madden, and Freeman [8]. from using the annual optima?…”

Section: Results Of the Analysismentioning

confidence: 99%

A Comparison of Annual Versus Average Optima for Fertilizer Experiments

Doll

1972

American J Agri Economics

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“…Confidence regions for annual optima would be of interest here and could be derived. See Heady, Jacobson, Madden, and Freeman [8]. from using the annual optima?…”

Section: Results Of the Analysismentioning

confidence: 99%

A Comparison of Annual Versus Average Optima for Fertilizer Experiments

Doll

1972

American J Agri Economics

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“…Weight of concentrates offered (C, lb OM/day) with roughage digestibility (D r ) were also tested as convenient expressions of dietary quality for practical application to mixed diets. Heady, Jacobson, Madden and Freeman (1964) considered interaction terms to be useful in their work on the milk production functions of the dairy cow and first order interactions were therefore tested on the more successful models.…”

Section: Methodsmentioning

confidence: 99%

Prediction of the voluntary intake of food by dairy cows: 1. Stall-fed cows in late pregnancy and early lactation

1970

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SUMMARYData from 22, 28, 36 and 41 pregnant cows in weeks 4, 3, 2 and 1 before calving respectively and 51, 65, 56 and 36 cows in weeks 1 to 4, 5 to 8, 9 to 12 and 13 to 16 of lactation respectively were used in multiple regression analyses to study the feasibility of predicting the daily total and the roughage organic matter and digestible organic matter intakes of cows given known weights of concentrates plus roughage ad libitum. The digestibility of the total intake and of the roughage component, the weight of concentrates eaten per day, the proportion of roughage in the total intake, age, milk yield, fat-corrected milk yield, live-weight gain and the 1·0, 0·73 and 0·66 exponents of live weight were used as independent variables.The accuracy of the models was assessed from the significance of the partial regression coefficients, the size of the residual standard errors, and the population tolerance limits about predicted values, and by applying selected models to a set of data not included in the study. The results indicated that the precision likely to be achieved in the prediction of intake for individual cows was of limited practical application, but the mean intakes of groups of 30 similar cows could be predicted with an acceptable level of accuracy for practical application. In general, weight of concentrates offered and the digestibility of the roughage were the most effective independent variables in all cows, together with milk yield in lactating cows. The application of the results to conventional feeding systems and to complete diets offered ad libitum is discussed.

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“…The nature of the production surfaces is similar, as can be seen by comparing Kansas Figures 1 and 2 with Figure 2 in Iowa Research Bulletin 529 [4]. The comparison is not entirely valid, because the Iowa diagram shows a single week.…”

Section: Ec Ahmentioning

confidence: 86%

“…Results of equations of types 1 to 6 appeared unsatisfactory when appraised against several selection criteria. 4 Initial criteria for choosing a set of production functions from which a final one was selected were (a) positive coefficients for the linear hay and grain terms, as well as negative coefficients for the squares of those terms to meet the requirement for diminishing returns, (b) coefficients for linear ability, weight, and maturity terms that were positive, and coefficients for the linear weight-change and temperature variables that were negative. From the equations that met the above criteria, further consideration was given only to those whose ridge lines, when plotted on the hay-grain plane, intersected at a point so that relevant isoclines (which also intersect at this point) were within the range of observed hay-grain input values (Figs.…”

Section: Estimating Equationsmentioning

confidence: 99%

“…Both authors recognized the inadequacies of their data and described their studies as primarily methodological and for the purpose of stimulating researchers to conduct experiments designed to permit estimation of milk production functions. This article reports one of a series of basic studies designed to specify economic optima for dairy-cow rations, following two earlier studies by the Department of Economics and Sociology and the Department of Animal Science at Iowa State University [3,4]. This study was designed to extend knowledge gained in the earlier analyses.…”

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confidence: 99%

See 1 more Smart Citation

Economic Relationships of Hay and Concentrate Consumption to Milk Production

Hoover¹,

Kelley²,

Ward³

et al. 1967

Journal of Farm Economics

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Additional knowledge about the nature of the milk production function and its economic and nutritional implications are reported in this interdisciplinary study by economists, nutritionists, and statisticians. A milk production response surface was estimated from a basic experimental design that included four rations (including all hay) and three levels of feeding. While complementing in part the design of earlier Iowa studies, additional attention was given to important economic, biological, nutritional, and statistical considerations. Results obtained provide additional evidence indicating nonlinearity of the milk production function and decreasing marginal rates of substitution of grain for hay. Inferences concerning conditions of economic optima are similar to those obtained in the Iowa research. While primarily methodological in nature, this research indicates the need for large-scale experiments to increase the precision of estimated parameters. Designs providing for estimation of experimental movements in both horizontal and vertical directions on the milk-hay-grain surface are needed. R ESEARCHERS in animal nutrition have sought for many years to develop systems of feed equivalents that would permit comparison of different feeds in terms of a standard unit. A serious criticism by dairy nutritionists of the feeding standards that have been developed is their lack of agreement in evaluating different feeds [5]. The linearity implied in these standards has been criticized by production economists [7].The pioneering study reported by Jensen et al. [6] gave evidence that the relationship of feed input to milk output is not linear, but the study was not designed to permit estimation of marginal rates of substitution between feeds.

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Milk Production Functions Incorporating Variables for Cow Characteristics and Environment

Cited by 15 publications

References 1 publication

A Comparison of Annual Versus Average Optima for Fertilizer Experiments

A Comparison of Annual Versus Average Optima for Fertilizer Experiments

Prediction of the voluntary intake of food by dairy cows: 1. Stall-fed cows in late pregnancy and early lactation

Economic Relationships of Hay and Concentrate Consumption to Milk Production

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