Recipient Organization
UNIVERSITY OF FLORIDA
G022 MCCARTY HALL
GAINESVILLE,FL 32611
Performing Department
(N/A)
Non Technical Summary
Increasing ruminant production to satisfy the demands of the global population is a growing challenge for producers. The solution is not as simple as raising the numbers of animals, given increasingly limited resources available. Instead, efforts should be directed at enhancing production efficiency. In that regard, differences in the microbial composition and activity of an animal's rumen are associated with ruminant production efficiency. Nevertheless, manipulation of the rumen microbial ecosystem remains one of the main challenges in the field, and the forces that determine its composition and activity are still poorly understood. In this application, we will investigate the role of milk secretory immunoglobulin A (SIgA) on the rumen microbial ecosystem. Our central hypothesis is that SIgA is an evolutionary mechanism responsible for assembling and maintaining the rumen microbiome. We postulate that the milk supply SIgA will accelerate the rumen microbiome's development, which will later be maintained by salivary SIgA. The supply of milk SIgA during early life will ultimately result in a beneficial microbial structure and functionality of the rumen leading to superior production efficiency. This hypothesis is based on our preliminary data. Understanding how to milk SIgA impacts rumen microbial assembly, composition, and activity is expected to have a substantial positive impact on ruminant production. This knowledge is likely to contribute to developing and disseminating strategies to modulate the microbial ecosystem and increase ruminant production efficiency. Thereby helping to ensure future global demands for safe and nutritious ruminant products are adequately met with agriculturally sustainable practices.
Animal Health Component
50%
Research Effort Categories
Basic
50%
Applied
50%
Developmental
(N/A)
Goals / Objectives
Our overall objective in this proposal is to evaluate the short and long-term impacts of early-life exposure to milk SIgA on the rumen microbial ecosystem and the efficiency of animal production. We will achieve the overall objective by pursuing the following twospecific objectives:Identify how the early-life supply of milk SIgA influences the assembly of the rumen microbial ecosystem as well as microbial diversity and activity during and after the intervention. Our working hypothesis is that the supply of milk SIgA will favor the assembly of the rumen microbiome. We also propose that SIgA modulates rumen composition and activity by binding to specific rumen microorganisms.Determine the effects of milk SIgA supply during early life on the production efficiency of dairy cows. Our working hypothesis is that exposure of newborn dairy calves to milk SIgA will enhance the ability of the animals to convert feed nutrients into milk and milk components.
Project Methods
We propose a long-term study to investigate how milk SIgA modulates rumen bacterial assembly, composition, and activity. In addition, we will look at the effects of milk SIgA exposure during the early life period on the production efficiency of dairy cows throughout their first lactation. Overall details of animal management can be found below, and a brief schematic of the experimental design can be seen in Figure 5. Forty-five female Holstein calves from the University of Florida (UF) Dairy Unit will be used in a randomized complete block design. Calves will be blocked by date of birth, and blocks will be balanced by calf body weight. From 2 to 28 days of age, animals will be assigned to 1 of 3 dietary treatments: 1) milk replacer without milk SIgA (control treatment), 2) milk replacer with 7.2 mg of milk SIgA per day, or 3) milk replacer with 7.2 mg of milk SIgA per day plus an inoculation with fresh rumen content collected from high feed efficient cows. The third treatment will allow us to test whether milk SIgA will bind to commensal bacteria and favor their establishment in the rumen. The SIgA dose and the supplementation period were defined based on our preliminary data (Study #4). Our goal is to mimic the milk SIgA consumption in a "natural" situation, so we considered an average of 700 μg SIgA per mL of milk and 8 L of milk intake per day, adding 7.2 mg of SIgA per day. The SIgA treatment will be provided until 28 days of age, which is when the secretion of salivary SIgA stabilizes. Details of SIgA isolation are provided below. Inoculation will consist of an oral and daily drench of rumen fluid (100 mL/animal during week 1 and 200 mL/animal thereafter). The selection of the donor cows and inoculum preparation are described below. After the treatment period (28 days), all animals will receive similar diets and management and will be assessed until the end of the first lactation cycle. This longitudinal experiment design will allow us to gain valuable insight into how SIgA modulates rumen microbial development and impacts community and function as well as assess the impact of SIgA exposure during early life on the efficiency of milk production.