Boatload of research from Minnesota

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Editor’s note: The following research summaries were provided by Noah Litherland, assistant professor and dairy cattle extension specialist at the University of Minnesota. The research was presented this past summer at joint annual meeting of the American Dairy Science Association and the American Society of Animal Science.

Transition cow nutrition and health

Title: Low cost on-farm predictors of individual cows risk for ketosis.
Authors:
Z. Sawall and N. B. Litherland
Objectives:
To develop a tool to predict cows at risk for subclinical ketosis.
Summary:
We developed a model we call "Pre-K" (predicting ketosis). This model uses body condition score and colostrum yield to predict cows at risk for subclinical ketosis. Using 200 cows in the University herd, Pre-K accurately identified 80% of cows that developed subclinical ketosis.
Take home message:
Cows with high body condition score have greater potential for body fat mobilization after calving. Colostrum yield is a good early predictor of energy demands (cows with high colostrum yield seem to produce more milk in early lactation). Cows with a body condition score over 3.5 and colostrum yield greater than 16 pounds are at risk for subclinical ketosis. Identifying and treating at risk cows for subclinical ketosis after calving may increase milk yield and decrease ketosis risk.

Title: Using early lactation milk fat to true protein ratio to evaluate transition cow success.
Authors:
Z. Sawall and N. B. Litherland
Objectives:
To determine if milk fat:protein greater than 1.4 is a valid predictor of cows at risk for ketosis.
Summary:
Cows with a fat:protein greater than 1.4 had an average blood ketone concentration indicative of cows with subclinical ketosis, fatty liver, and lost more body weight after calving.

Title: Effects of varying transition cow dietary starch concentration and supplementation with propionate producing direct fed bacteria on transition cow performance and metabolism.
Authors:
Z. Sawall, T. Parrott, W. Weich, D. Lobao da Silva, and N.B. Litherland.
Objectives:
To determine the effects of feeding direct fed microbial (DFM) and varying starch amount (20 vs. 29%) on feed intake, energy balance, and milk yield in transition cows.
Background:
Early lactation cows have greater feed intake and milk production when fed a reduced starch diet during early lactation. Feeding a high starch diet, similar to that typically fed to high producing cows, may not be ideal for fresh cows. Propionate, a volatile fatty acid produced by rumen bacteria is used to make glucose in the liver and is then converted to milk sugar (lactose) in the mammary gland.
Summary:
Starch concentration did not affect milk yield or feed intake, but tended to increase blood ketones. Propionate producing DFM increased feed efficiency during early lactation. The combination of a high starch diet and DFM resulted in the greatest milk production, but the increase in milk production did not occur until week 5 of lactation.
Take home message:
Low starch diets resulted in similar milk production in the first month of lactation compared to high starch diets. Fresh cow diets should optimize fiber digestion (good quality forage and avoid high starch diets). A pen dedicated to fresh cows allows producers to feed a diets specific to meet fresh cow needs.

Title: Effects of varying early lactation dietary starch concentration on first calf heifer performance and health.
Authors:
Z. Sawall, T. Parrott, W. Weich, D. Lobao da Silva, and N.B. Litherland.
Objectives:
To determine the effects of feeding 21 vs. 29% dietary starch on feed intake, milk yield, and body fat mobilization in first calf heifers.
Background:
Heifers represent a very important group and their early lactation nutrition and management has a significant impact on their first lactation performance.
Summary:
Varying dietary starch concentration did not alter feed intake. The high starch diet tended to increase yield of 3.5% fat corrected milk. High starch diets increased the risk of metritis, ketosis, and fatty liver after calving.
Take home message:
Low starch diets in early lactation reduce the risk of ketosis and fatty liver, but may also decrease milk production. High starch diets might impact first calf heifers more than cows.

Forage digestibility

Title: Effects of supplemental sugar on fiber digestibility of corn silage.
Authors:
D. Lobao da Silva and N. B. Litherland.
Objectives:
To evaluate the effects of varying source of supplemental sugar on fiber digestibility of corn silage.
Summary:
Pure sugars lactose and sucrose increased fiber digestibility over control. Due to their purity, both lactose and sucrose delivered the greatest amount of sugar indicating that the effect of sugar on rumen fiber digestion is dependent upon the concentration of sugar in the diet and also perhaps the chemical profile of the sugar.
Take home message:
The effects of supplemental dietary sugar on rumen fiber digestibility are dependent upon the concentration of the sugar in the diet and the potential fiber digestibility of forage in the diet.


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