Butterfat is increased by increasing the number, and protecting the conditions which are beneficial to cellulose digesting, acetate producing,bacteria in the rumen.

Don’t over feed supplement.
Supplement should not exceed 50% of the diet. In their effort to make more milk, producers will often overfeed supplement. This reduces butterfat, especially when the supplement to forage ratio approaches2:1. Concentrates are too quickly digested and with the correspondent drop in the need for saliva production, you get a drop in rumen pH, which is harmful to the microbes that produce butterfat.

Feed roughage before you feed grain in the morning.
Again, having hay in the rumen first will slow down digestion, ensure adequate saliva production and keep the rumen pH at a favorable level for acetate-producing microbes.

Take the total amount of supplement the goats need to eat during a day, and feed it in several small meals instead of giving it in only two larger meals at milking time..
Again, this optimizes the conditions beneficial to microbes. It takes time to feed more often, so producers will have to decide how badly they want higher butterfat.

Provide good ventilation, plentiful water and multiple smaller meals when it is hot outside. Goats eat less when it is hot, so you will often see a drop in butterfat in the summer due to a drop in intake of feed.. Anything you can do to help them eat more will increase butterfat. Increased intake increases the heat of digestion in the rumen, and that in turn increases acetate production and raises the level of butterfat.

Feed good quality forage. If you have only poor quality forage, add buffer to the diet.
Low-roughage fiber intake lowers butterfat. Supplement the diet with buffer at a rate of 4% of the amount of supplement fed per day to increase butterfat production when feeding poor quality forages. (Note:many goats do not like buffer in their feed, and will completely refuse to eat the ration with it in there, but will take it readily when it is offered free-choice in the barn or lot.

Feed larger quantities of dried brewer’s grain.
Research show that distillers grains contain yeast by-products that stimulate rumen cellulose digestion, which results in acetate formation, thereby increasing butterfat.

Breed for high butterfat as well as high milk production.
When selecting breeding stock, if you select for high milk production alone, don’t pay attention to butterfat levels, you will gradually see decreased butterfat from one generation to the next..

(Smith, 485)

Link: Variations in Milk Fat Composition: Why do my milk processorand DHIA tests not always agree? http://extension.usu.edu/files/publications/newsletter/pub__4960713.htm

What is Toxoplasmosis?

http://www.cattlenetwork.com/cattle-resources/cattle-breeds/angus/Livestock-producers-may-see-lowered-fertility-in-herds-this-fall-167351815.html

Note the heat effect on male animals. 71 days for bulls, 56 for rams and potentially bucks. He says that it is not expected to affect long-term fertility, just X-days from extreme heat.

From Dr.David Fernandez, U of AR

Livestock producers may see lowered fertility in herds this fall

Arkansas Division of Agriculture
Updated: August 28, 2012

PINE BLUFF, Ark. – As if drought damage to pastures and high hay and feed prices aren’t enough, livestock producers may see reduced fertility in their breeding herds this fall, says Dr. David Fernandez, University of Arkansas at Pine Bluff Cooperative Extension Program livestock specialist.

“The exceptionally high heat could impair the ability of bulls, bucks, rams and boars to produce viable sperm,” he says. Cows, does, ewes and sows may produce less viable eggs or experience higher levels of early spontaneous abortions.

Here’s why. Most male mammals’ testes are located in the scrotum outside their bodies. This allows the male to maintain his testes at a temperature several degrees below his body temperature which is essential for sperm production. When temperatures exceed 103 F for several days, the testes cannot be cooled adequately, and sperm production can be impaired, says Dr. Fernandez.

The damage to sperm production can be long term. Sperm production in the ram requires an average of 47 days plus another nine days for the sperm to migrate to the storage area. That’s 56 days. Similar time frames are believed to exist for bucks. For bulls, it is more than 70 days. The damage is not readily apparent, he says. In some cases, the number of sperm and their motility may be reduced.

“Much of the damage appears to be done to the DNA of the sperm,” he says. This means that a sire may appear to be normally fertile after a breeding soundness exam, but pregnancy rates of dams may be low, with many repeat breeders.

Compounding the problem are the effects of high heat on female reproduction. When temperatures are high, eggs may be less fertile and may not survive to form a viable embryo after fertilization. Fortunately, the effect of high temperatures on females tends to be limited to the estrus cycle in which it occurs.

“Unfortunately, no cost effective on-farm method exists to determine whether the problem is with the male or female,” says Dr. Fernandez, who advises that the best thing to do is to provide plenty of cool water and shade to help keep livestock cool. Also, monitor the herd’s nutrition as they may not eat enough feed when days are extremely hot.

Finally, producers should plan ahead so they are prepared if their herd’s breeding season begins and ends later than usual. And, investigate alternative marketing strategies and parasite management schemes for next spring and summer, he says.