Fat Supplementation
Reproductive efficiency is a critical factor in the profitability of a producer’s operation. Research at Ft. Keogh Station, Miles City, MT indicates vegetable-based fat in the diets of reproductive females may maximize reproductive performance (Table 3).

 

Table 3 Effect of High-Fat Diets Fed 50 Days Prior to Calving on Beef Female Reproduction
	Control	Treatment
No. of head	76	76
Fat level, %	2	4
Days fed	50	50
Weight change, lb	173	156
Cycling, %	78	76
Pregnant, %	79	92
Weaning weight, lb	402	432

Source: USDA-ARS, Miles City, MT

Since the research trial was isocaloric (same energy levels), the increased reproductive efficiency was not due to increased energy in the diet. The positive effect of fat on reproduction is believed to be due to the elevation of cholesterol, progesterone, luteinizing hormone, and growth hormone, which occurs when supplemental vegetable-based fat is fed. It also appears vegetable fat increases embryo survival rates.

The four-year summary of work on reproductive efficiency done with vegetable-based fats indicates the following:

• Average increase in pregnancy of over 10%

• Average increase of 30 lb in weaning weights from first-calf heifers

• Slight increase in birth weight and calving difficulty

• Increase in calf’s ability to handle cold stress

• Amount of supplemental vegetable fat fed needs to be at least 0.4 lb per head daily

• Practical use of high-fat supplements is with two- and three-year-old cows, late calving cows, and cow herds with a high percentage of late calving cows or with a low reproductive rate.

• Very thin cows (<BCS 4) don’t respond as well to fat supplementation compared to cows in better condition

Feeding supplemental vegetable-based fat to improve reproductive efficiency should be considered in a Year-Round Range Program.