Level of Canola Source Fat in Pregnant Beef Cow Diets - Effects on Cow and Calf Performance

Background

In a previous study, researchers at the University of Saskatchewan found that supplementing cows with canola pellets in the second and third trimester resulted in calves that were bigger, grew better and had a higher carcass weights than calves from dams that weren’t supplemented. Calves from supplemented damns had carcass weights 48 lbs. higher than those whose dams weren’t supplemented. In this trial dams were fed diets that contained the same among of energy, it was just the source that it came from that was varied (barley grain vs. canola pellets). Also all calves were fed the same diets from birth to finishing so any differences seen were assumed to be due to dam supplementation. Researcher also found that dam diet affected the expression of a gene that controls muscle growth and development, suggesting that supplementing during pregnancy may alter the way genes that control calf growth are expressed.

Objectives

•  Identify optimal amount of fat from canola seed supplementation in the diet that will lead to improved performance in both the dam and progeny.
• Discover if differences due to prenatal fat supplementation affect adipose tissue fatty acid composition, milk yield, milk composition, and the fatty acid profile in milk.
• Determine if calves from cows fed differing levels canola seed supplementation have enhanced passive immune transfer and reduced paracellular permeability.

What they will do

In this trial researchers will build on previous work to take a closer look at how supplementation of the cow is affecting calf gene expression. Twelve groups of six cows each will be fed one of four different diets. Diets will contain either 0, 150, 300 or 450 g/cow/day of fat from a canola based pellet. Cows will receive the treatment from the start of the second trimester until 50% of the cows have calved.  Calves from all dams will be managed similarly from weaning through to slaughter. Calf weights will be measure throughout as well as dry matter intake during backgrounding and finishing and carcass traits.

Colostrum will be collected and analyzed for composition and Immunoglobin levels, cows rebreeding percentage will be recorded, and calves will be tested for serum IgG levels 24 hours after birth to test for passive immunity transfer. They will also collect DNA, tissue, and muscle samples. Carcass data will be collected and analyzed and economics on supplementation will be performed.

Implications

Calves that gain more and are healthier are an asset at both the cow-calf and feedlot levels. This project will help determine why fat supplementation increases calf performance, and eventually could lead to management practice that would increase calf growth.