ORCID
0000-0003-4734-4137
Date of Award
2025
Document Type
Thesis
Degree Name
Master of Science (MS)
Department
Animal Biosciences
First Advisor
Joao Costa
Second Advisor
R. Chris Skinner
Abstract
In the last decade, there has been growing scientific and industry interest in the early-life nutrition of dairy calves. New trends in milk replacer formulations as an alternative to the use of cow’s milk have gained popularity. Among macronutrients, dietary fat not only supplies energy but also influences satiety, nutrient utilization, and supports the transition from liquid to solid feeding in dairy calves’ diets. As dairy systems shift toward high liquid diet allowances, there is growing concern that excessive fat levels may suppress solid feed intake, delay rumen development, and impair long-term performance. Improvement on processing technologies and the importance of fat composition on calf health and development have driven efforts to find suitable alternative fat sources that resemble cow’s milk fat composition in milk replacers formulations. Despite the advances, the optimal level of fat inclusion in milk replacer as well as fat blends that can be tailored to modern pre-weaning diets remain areas of active investigation. The primary goal of this thesis was to evaluate the effects of varying inclusion levels of fat and ratios of coconut to palm fat in milk replacer on solid feed intake and performance of pre- and post-weaned dairy calves fed a high milk allowance feeding program. Two randomized controlled trials were conducted using individually housed male Holstein calves. In the first study, calves received milk replacers formulated with 26 % crude protein and a spray-dried fat blend (20 % coconut to 80 % palm fat), varying fat inclusions on a dry matter basis: low (17 %), moderate (24 %), or high (31 %). In the second, all calves received milk replacers with equal fat and crude protein content (21 % fat; 26 % crude protein), but with varying ratios of coconut to palm fat in a spray-dried fat blend (20:80 %; 35:65 %; 50:50 %). All calves were raised under a step-up/step-down feeding program and had ad libitum access to water and calf starter. Body weight, solid feed intake, water intake, and health events were recorded throughout the study. In the first study, reducing fat (17 %) in milk replacer increased solid feed intake, resulted in greater performance and feed energy efficiency than calves fed higher levels of fat. These improvements were mainly observed after weaning, suggesting that reduced fat levels may have promoted greater solid feed intake and facilitated a smoother transition to solid diets. In the second study, a milk replacer including 21 % of fat in the DM with a spray-dried fat blend containing 35 % coconut to 65 % palm fat ratio supported a greater performance. This suggests that the specific combination of medium- and long-chain fatty acids may have improved nutrient metabolism. Health outcomes, such as diarrhea and respiratory issues, were not different across all treatments in both studies. These findings suggest that both the level and composition of fat in milk replacers can modulate solid feed intake, resulting in better performance, when calves are fed high milk allowance. Future studies should investigate phase-feeding strategies, body composition, and how different fat levels and fat composition interact with hormonal and metabolic pathways to improve our understanding of the mechanisms behind these feeding strategies that promote smoother weaning transitions.
Language
en
Number of Pages
146 p.
Recommended Citation
Ribeiro Lovatti, Joao Vitor, "The Effects Of Fat In Milk Replacer On Performance And Solid Feed Intake Of Pre-Weaned And Post-Weaned Dairy Calves: Fat Levels And Fat Ratios Of Coconut To Palm Fat" (2025). Graduate College Dissertations and Theses. 2116.
https://scholarworks.uvm.edu/graddis/2116