Breeding and Genetics III: Methods

Concerns have been raised in the past about the Dairy Herd Improvement Association recording frequency, because the interval between samples, about 4 weeks, may not capture the peak production for cows with shorter lactation (less than 10 mo), which have led to the conclusion that these cows have an atypical lactation curve shape. This may be due to sampling frequency rather than biological differences of cows or the influence of biotics and abiotics variables. Geometric morphometrics is a methodology that is used to measure biological shapes and curves, which has already proved its application in biology, medicine, and engineering. This methodology can be used for quantifying, testing, and visualizing shape variation and its covariation with biotic and abiotic variables. We propose to apply this method to determine the variation and covariation of lactation curves for milk, fat, and protein production. Daily records of milk production and fat and protein concentration collected by the AfiLab recording system (Afimilk, Kibbutz Afikim, Israel) from January 2014 to January 2017 from 47 large kibbutz (communal) herds distributed throughout Israel, will be analyzed. Lactation data will be plotted into an orbital graph to depict a closed curve. Currently methods to predict future lactation prediction of individual cows are based chiefly on production on the last available test day. Using geometric morphometrics it should be possible to derive more accurate estimates of future production, which can be used both to improve management decisions and genetic evaluations.