As dairy producers search for solutions to ongoing reproductive challenges, nutrition remains one of the leading avenues to improve breeding pen success. New research presented at the 2010 ADSA meetings by Drs. Jose Santos, Bill Thatcher and Charlie Staples, reported new results further linking nutrition to production performance, reproductive success and health through essential fatty acid (EFA) supplementation.

Critical to breeding pen success

EFAs – specifically Omega-3 (18:3 linolenic) and Omega-6 (18:2 linoleic) – serve key functions related to dairy cows’ reproductive health and performance, including:

• Supporting the production of specific reproductive hormones, especially progesterone. Higher concentrations result in stronger heat signs and improved heat detection, conception rates and pregnancy maintenance.
• Aiding in the production of prostaglandins. These cause ovulation and a subsequent estrous cycle. In addition, they enhance visible signs of heat and increase blood flow to the ovaries to promote follicle growth.
• Promoting cell wall integrity

Achieving these benefits can be challenging as cows may not consume enough EFAs through commodity feed sources typically included in the diet. While several feeds, like cottonseeds and whole soybeans, contain certain levels of EFAs, they are often altered in the rumen through biohydrogenation, making them unavailable as EFAs and useless to meet daily requirements.

Based on the known importance of EFAs to reproduction, the University of Florida conducted research to take current knowledge to the next level, explains Dr. Jose Santos, lead researcher of the trial. The in-depth study was designed to further detail the mechanisms by which Omega-3 and Omega-6 EFAs impact reproductive performance, health and production, as well as their effect on calf health through prepartum supplementation.

Study design

This study enrolled Holstein cows into one of three groups at an average of 56 days prepartum; the study included both first-lactation and second-lactation and greater animals. All cows remained in the following groups through 95 days in milk:

• Group 1: Control diets were not supplemented with fat.
• Group 2: Cows were fed saturated fatty acids at 1.75 percent of dry matter.
• Group 3: Cows were fed calcium salts of unsaturated fatty acids enriched in Omega-3 and Omega-6 EFAs at 2 percent of DM (the same level of total fatty acids as fed to Group 2).

Cows were monitored weekly for bodyweight and body condition score (BCS), while blood tests were conducted to evaluate a variety of different measurements. As cows entered the postpartum phase of the study, more intense blood sampling was done to evaluate immune response.

Additionally, in the first 40 days after calving, cows were ultrasounded four times weekly to monitor uterine involution and follicular development. Cows were also synchronized to evaluate embryo quality. Furthermore, cows were monitored for milk yield, milk composition and dry matter intake (DMI).

Multiple benefits reported

• Improved reproduction. Although the study was not designed to evaluate fertility, the group fed EFAs had numerically higher pregnancy per insemination, Santos says. Final data analyses of embryos collected on days seven and 15 after insemination is still underway at the University of Florida.
• Increased feed efficiency. Cows consuming a ration containing the supplemented EFAs improved feed efficiency, producing higher milk yields per pound of DMI ( Table 1 ).
• 

  Maintained DMI. Feeding supplemental EFAs did not suppress DMI as compared to the control group. And the source of EFAs did not impact the bodyweight or body condition score of animals.

An unexpected result in the trial was the significant increase in milk yield when EFAs were fed. One hypothesis is that Omega-6 EFAs in the dairy cow’s diet might influence mammary cell activity, which may have been the cause of the increased milk production.

In addition to the positive effects seen in lactating dairy cows fed supplemental amounts of EFAs, calves may also benefit. A secondary part of the study tracked the health of calves born to a mother fed the EFA diet prepartum.

At birth calves were given 4 liters of colostrum from their own dam or from a dam fed the same dietary treatment as the calf’s dam. Following the initial colostrum feeding, calves were fed one of two milk replacers containing low or high amounts of Omega-6 fed for 60 days, with these results:

• Feeding fat prepartum resulted in greater lgG concentration in colostrum and improved IgG absorption efficiency. Higher concentrations of the IgG antibody provide additional immunity for the calf against potential invading pathogens.
• Increasing Omega-6 in milk replacer from 2.8 to 8.8 grams per day improved calf daily gain and weaning weight.

Future research opportunities

These initial results lay the groundwork for unlocking new information to improve dairy cattle reproduction, health, immunity and milk production. Future research may include:

• Dietary requirements. The optimal amounts of EFAs in the diet are still unknown; future research will provide producers with the correct levels of Omega-3 and Omega-6 EFAs to include in the diet for lactating dairy cows.
• Precise delivery. EFA levels absorbed in the small intestine may be much lower than the ration is formulated for based on the feed source utilized. Better methods to measure the absorption of EFAs in the small intestine will uncover with more precision the amounts of EFAs necessary to achieve optimal results. Currently available feed ingredients can also protect Omega-3 and Omega-6 EFAs until they reach the small intestine for effective delivery of these important nutrients.
• Impact on reproductive tissues. Studies are underway to understand how EFAs influence expression of genes potentially associated with fertility of dairy cows. Benefits to fertility are associated with these fatty acids, signaling the expression of genes in the embryo and the uterus of the cow that might facilitate establishment and maintenance of pregnancy.

Based on the research results, feeding EFAs offers a variety of productivity, health and profit opportunities for your herd. Harnessing the new research findings in your nutrition program can deliver exciting benefits for peak milking string performance and reproductive success. PD

• Elliot Block

• Senior Manager of Technology
• Arm & Hammer Animal Nutrition
• Email Elliot Block