Genomic selection for profit and antibiotic reduction
It is easy to breed for production or type, but how can you breed to reduce antiobiotic use? Looking at current bull data the only relevent data is longevity, somatic cell count and perhaps condition score. Zoetis’ Genomic evaluation with CLARIFIED Plus (https://www.zoetisus.com/animal-genetics/dairy/clarifide/clarifide-plus.aspx) now includes specific health trait evaluations including mastitis, metritis, lameness, calf respiratory and cow respiratory. Ranking cows on their mastitis score alone shows that the top 25% of cows use 65% less antiobiotics than the bottom 25% which was an average of 1.28 fewer inter-mammary tubes per cow. It is never recommended to use single trait selection, so Clarified have developed a Dairy Wellness Profit (DWP) index which combines production, type, fertility, longevity and health traits. Analysis made based on the balanced DWP index still shows the top 25% of cows using 44% less antiobiotics for mastitis. DWP figures are only available on Jersey and Holstein bulls. Genetic gains can be made by just using the highest DWP bulls, but the greatest advance comes with genomic testing of females and exerting selection pressure on which females are bred from. Use of sexed semen can have a big effect in making more progress. Breeding for DWP not only reduces antibiotic use, but it is a selection tool that can have an important financial impact on a dairy by increasing lifetime milk production, milk per day of life, herdlife and expected profit per cow. Improvements can be expected in calf mortality, ketosis, displaced abomasums, milk fever and cystic ovaries.