Recorded live at the American Dairy Science Association (ADSA) 2026 Meeting, this episode features Giovanna Evangelista, master's student at the University of Florida, and her advisor, Dr. José Santos, Professor in the Department of Animal Sciences at the University of Florida. They discuss Giovanna's poster, "Phenotypic and Genetic Associations with Colostrum Yield and Composition in Dairy Cows." The conversation covers which cow- and calf-level factors, nutrient intake and genetics influence colostrum production, helping answer common producer questions about colostrum yield and quality.
The episode opens with introductions. Dr. Santos, who has been at the University of Florida for almost 20 years, explains that Giovanna's undergraduate mentor at the University of São Paulo was his friend from grad school at the University of Arizona. She came to Florida with high recommendations after an externship at the University of Georgia. (00:00 – 03:06)
The discussion then shifts to Giovanna's study design. The data set included over 4,000 animals across 11 experiments and 38 treatments. About 21 phenotypic factors, including calving season, parity, dry period length, calf birth body weight, cow body weight, retained placenta and metritis, were first tested in univariable models. Factors with P ≤ 0.20 moved forward, and those with P ≤ 0.10 were kept in the final models for colostrum yield, fat and IgG. (03:07 – 05:01)
Giovanna then shares the colostrum yield results. Cows produced more colostrum in fall and summer, multiparous cows produced more, and a longer dry period was positively associated with yield. Surprisingly, dry matter, metabolizable protein and net energy intake had no significant association with colostrum yield, and the slope was actually negative. Cows that produced more colostrum also performed better in the first 10 weeks of the next lactation. (05:02 – 06:52)
A key theme of the episode is questioning the common advice to feed more protein before calving when colostrum is poor. Dr. Santos notes that cows eating 800 g of metabolizable protein showed no difference in colostrum yield compared with cows eating 1,400 g. He calls the strong genetic component, with moderate to high heritability, the nicest finding. It suggests cows could potentially be selected for better colostrum yield and composition, possibly as a trait separate from milk yield. (06:53 – 10:11)
The conversation also covers the biology behind colostrum IgG. It's still unknown whether colostrum IgG comes only from maternal blood or also from plasma cells in the mammary gland. Giovanna hopes to use RNA sequencing of the placenta to see whether a missing Fc receptor explains why IgG doesn't cross it. She also plans nutritional experiments to see whether specific nutrients change colostrum IgG. (10:12 – 13:01)
Next, Giovanna shares her plans to pursue a PhD and likely work in industry in the U.S. Dr. Santos points out research gaps, including limited data on immunoglobulin transporters in the ruminant placenta and how colostrum is made in ruminants. Much of that data currently comes from laboratory animals. (13:02 – End)
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