By Holtz, C. R. and Jones, L. R., Journal of Dairy Science, 1990
Description
A user-friendly microcomputer program was developed to provide an interactive tool to analyse lactation curves graphically. One method of evaluating lactation curves is to plot a composite curve for a contemporary group of animals. Groups can be defined by parity number (e.g. 1, 2, 3+) and according to days in milk or month of calving, thus allowing for evaluation of varying stages of lactation as well as management and/or seasonal changes. To provide a reference, standard lactation curves according to rolling herd av. level (5445-10 890 kg by 454 kg increments) and parity group (1, 2, 3+) are also provided. The group lactation curves can be compared with a standard curve to determine sub-standard performance (e.g. low peaks or poor persistencies) and to identify groups that may be performing below management capabilities. A higher standard can also be chosen to evaluate necessary changes for improving performance. The impact of management changes and herd problems can be observed with changes in the shapes of curves. Such information allows managers to focus on specific segments of a herd regarding nutrition, body condition, grouping strategies and other management factors. Caution should be observed, however, when drawing conclusions about a small group of animals at a single data point (e.g. <10 observations). The other method for evaluating lactation curves is for individual cows. This method can reveal the impact of independent animal problems (e.g. laminitis, metabolic disorders) and management problems that can be masked in a group composite curve. In this mode, the program provides other desciptive information (e.g. percentage milk fat, percentage protein, reproductive status, linear score, etc.) that can be utilized in making management and culling decisions regarding the animal. Users of the program report excellent results in terms of being able to define and display lactation curves graphically for evaluation of herd management practices and abilities
A user-friendly microcomputer program was developed to provide an interactive tool to analyse lactation curves graphically. One method of evaluating lactation curves is to plot a composite curve for a contemporary group of animals. Groups can be defined by parity number (e.g. 1, 2, 3+) and according to days in milk or month of calving, thus allowing for evaluation of varying stages of lactation as well as management and/or seasonal changes. To provide a reference, standard lactation curves according to rolling herd av. level (5445-10 890 kg by 454 kg increments) and parity group (1, 2, 3+) are also provided. The group lactation curves can be compared with a standard curve to determine sub-standard performance (e.g. low peaks or poor persistencies) and to identify groups that may be performing below management capabilities. A higher standard can also be chosen to evaluate necessary changes for improving performance. The impact of management changes and herd problems can be observed with changes in the shapes of curves. Such information allows managers to focus on specific segments of a herd regarding nutrition, body condition, grouping strategies and other management factors. Caution should be observed, however, when drawing conclusions about a small group of animals at a single data point (e.g. <10 observations). The other method for evaluating lactation curves is for individual cows. This method can reveal the impact of independent animal problems (e.g. laminitis, metabolic disorders) and management problems that can be masked in a group composite curve. In this mode, the program provides other desciptive information (e.g. percentage milk fat, percentage protein, reproductive status, linear score, etc.) that can be utilized in making management and culling decisions regarding the animal. Users of the program report excellent results in terms of being able to define and display lactation curves graphically for evaluation of herd management practices and abilities
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