"This is not just BS or conjecture, it's based on my experience and now I've found another person who has had the same thing happen.
The bottom line is that if you are feeding beef from the usual USDA sources that are not organic and grass fed, the hormones they use in the meat affect the heat cycles of b###hes, the sperm production of males, the temperaments of the dogs and the fertility damage may be permanent. Here is a link to the FDA which lays out the rules for adding hormones to cattle for beef:
As you see, they are not allowed to add hormones to dairy cattle, veal calves, pigs, or poultry. That means poultry is one of the safest of the commonly found protein sources for us to feed. My dogs stopped coming into heat for over 3 years and one young b###h, the last of my line, has never come into season again, a huge loss to my breeding program. Her mother started to come in heat again, but never was able to get pregnant. Three of them also got pyometra which I know was related to the beef diet as the likelihood of 3 dogs getting it within a short time is close to nil.
Additionally, the temperaments changed on all of my dogs. Dogs that had always gotten along well with each other started getting prickly and fighting with each other. They became very hyper and "off-the-walls". I could not understand what in the world had happened to them. After a couple of years of this and after doing research, I put 2+2 together and thought it could be the beef I was feeding. I took them off of beef and went to organic chicken, and after about 2-3 months, everyone started calming down again and after about 6 months, with the exception of the one, they all started cycling normally again. I did not have a trustworthy and affordable source of organic grass-fed beef, so I went to the organic chicken.
Yesterday, I e-mailed a breeder I hadn't spoken with in a while, and feeding was brought up the conversation. She feeds a commercial raw, a brand she has used for many years. She said she uses the beef mixture as the dogs liked it best. I told her the experiences I had while feeding a solely beef based diet for a number of years, only to find out that she too has not been able to get anyone pregnant for a long time!! I was so thankful I was able to tell her about this, me not even knowing she was having issues when I told her.
Organic beef cannot have hormones added. Here is a paper describing the guidelines for raising organic livestock:
But guess what, they are finding that they are still using hormones in non-organic species that are listed by the FDA as not allowed to be ones that can receive hormones:
"Illegal Hormone Use in the Veal Industry
The veal industry has recently been found guilty of using banned hormones in growing up to 90% of its veal calves and this has reportedly been common practice for decades[vi] <#6> . These hormones include all six HGPs approved for use in adult cattle, namely testosterone, progesterone, trenbolone acetate, 17 beta-estradiol, zeranol, and MGA but they have never been approved for calves. The safety or side effects of injecting calves with hormones intended for heifers and steers over 700 lbs has never been evaluated, but it is suspected that these hormones may be metabolized differently in the young calf's body which could lead to greater amounts of hormones consumed by people who eat veal."
Anyway, keep all of this in mind as you feed your dogs. The hormones can affect both males and females and they build up slowly over time till all hell breaks loose. In my case it took 1-1/2 to 2 years for the hormone problems to show up and about a year (or a little less) for the temperament changes to ensue."