Reproduction Performance (Butter-fat). By Gearld Fry, reprinted from Cowboy Wisdom, Jan 2012
Reproduction in our livestock herds is the highest sought after production trait and sadly the most misunderstood and misrepresented of all of them. Obtaining high reproductive performance is a genetic selection process and the role the bull plays is just as important as the role of the cow. The overwhelming majority is for a fact, trying to accomplish their reproduction goals using inferior bulls. James Drayson’s research presented later should help you to understand the different performance levels including the top level of breeder bulls.
A survey taken a few years ago revealed that only 70% of the cows in an average herd produce a live calf in a consistent12-month interval. The percentage is even lower in the south.
Many producers leave the bull with the cows all the time. In this scenario the cows conceive when their available energy reaches an adequate level that coincides with the quality of the bull’s semen. A cow may begin ovulating earlier in her lactation but because of the low quality (germ plasma) sperm of the so-called herd sire the sperm is not strong enough to fertilize the ovum and the cow remains open. As a result, so many ‘open’ cows are sold when there is really nothing wrong with them reproductively speaking. While the cow is viewed as the one not being able to conceive, it is more likely, from my experience, that the bull is not strong enough reproductively to get the job done even though a semen test done before breeding season indicated he should have been.
Open cows are always getting the blame when in fact they are only half of the reproduction equation. Bulls get the blame only when there is an obvious physical problem, but it’s the unseen (microscopic) that I want to address. A complete semen test takes a number of things into account to fully assess the breeding ability of the bull. When one or more of these different factors aren’t considered and evaluated there is no way of knowing there’s a lurking problem and thus the reason for most open cows. I’ll go into more detail in just a bit.
Taking a look at the female, most cattlemen are of the mindset that heifers should calve by the time they reach 2 years old. Those 14-month-old females are most often put in with the bull a few weeks earlier than the mature cows believing they need a little more time to get pregnant. This management strategy is also used for the second pregnancy. If this was truly effective than why haven’t pregnancy rates improved, because they haven’t.
There are three growth development processes that have to take place in the bodies of our young heifer calves (male calves too) and if these developments do not happen for whatever reason under the current management, pregnancy rates cannot be expected to improve.
These growth development processes are (#1) bone or frame growth, (#2) building muscle mass and (#3 – is the most critical and least considered) – fat cell production. Fat cell formation and location along with an increase in their number and size are the precursors and mechanism for the proper development and functioning of the animal’s endocrine or gland system. Reproductive performance is directly correlated to the health functioning of the gland system.
Out of all the nutrients that make up a young bovine’s diet there is one in particular that determines how well these three processes can occur. The availability of this form of nutrition starts at conception and the ability within the mother cow to manufacture it is a genetic trait. I shall refer to it as butter-fat or milk butter-fat. The diary industry measures cows’ milk-fat or what most think of as the cream. I am referring to the more fundamental fatty acids; the essential oils that are contained in the cream that we humans use to make butter
From conception and for the next three months the fat cell placement pattern is being set in the developing fetus. This pattern is an inherited trait passed down from the genetic profiles of the sire and dam. From birth up until weaning (8-10 months old) these fat cells build in number. And from weaning on up to about the age of 18-20 months those fat cells are filling, they’re enlarging, getting bulky. The rate and extent that those fat cells build in number and fill to capacity correlates with availability and quality of nutrition beginning at conception.
The physical structure of the newborn calf is the result of its genetic predisposition and intra-uterine nutrition. If the cow had good nutrition (nutrient dense grass) and carries the trait for high butter-fat milk then the calf is the picture of that perfect nutrition. If her nutrition was poor, her fetus and resulting calf will be functioning at a deficit and most likely never reach optimal performance. One side note to remember, if the genetic trait passed on was to deposit fat cells outside of the flesh (as opposed to inside or intramuscular) it gets deposited along the connective tissue the resulting carcass will be tough. You cannot feed quality and tenderness into an animal.
The next window of opportunity for proper development to occur is that period from birth up to 10 months. While building bone and frame along with muscle mass (what we see), the fat cell development process is happening too. There’s a lot going and if the nutrition isn’t there, meaning high butter-fat milk, something gets compromised. If it doesn’t happen within the first 10 months it won’t happen properly or successfully for the producers’ best interest or profitability.
We know from dairy industry data and the comprehensive research done to develop milk replacers what amounts of nutrients (especially fat) a calf needs to survive, to thrive, or to excel in performance. Looking at the typical beef cow that produces around 4,000 lbs. of milk per lactation, if she gives milk that is 4.5% butter-fat, that is the right amount (180lbs) of the fat portion of the calf’s diet for it to complete the 3 development processes and be a high functioning animal. The fundamental components that are in the butter-fat (fatty acids, essential oils, etc.) are responsible for quick energy, stored energy, hormone production and meat quality.
Only those young females whose mothers provided 180 lbs. of fat (more is fine) are the ones that can get pregnant at a young age and then breed back on time for their second calf. The fat cells in these young females are full and are a source of instant and sustained energy to get the job done. We need to be selecting for this genetic trait if we expect to improve reproduction and be profitable on grass.
Back to the breeding of 14 month old virgin heifers, at 14 months of age only about 60% of those heifers are pregnant at the end of the 90 day breeding season, so if the bull is removed 40% are open and get sold. For the second calvers, the percentages are about the same, 60% get pregnant while 40% remain open, so those females end up getting sold along with the mature cows that don’t pass a pregnancy test. In effect this conventional management practice of selling open or those deemed reproductively unsound heifers and cows has eliminated the issue of low fertility on the maternal side. A huge problem as I’ve seen it, is thousands of good cows are sacrificed (slaughtered) at the altar of low fertile bulls.
To find the answer of why so many open cows, we must look in other places. I discussed earlier the reason why our mother cows need to be able to supply about 180 lbs. of butter-fat for their growing calves. The three growth development processes don’t happen completely and successfully together with lesser amounts. Cows can easily produce this quantity of fat in the milk, however because of the selection, breeding, and management practices that have ruled our industry over the last 50-60 years, our cows are heterozygous in their genetic make-up and just because a cow produces some fine daughters does not mean those daughters have inherited the same ability.
Only about 5-10% in any herd are capable of producing 4.5% butter-fat milk. That means a high percentage of herd sires come from cows that don’t fall into this category thus they themselves are compromised along the way in their development resulting in an inferior functioning gland systems that as a result affect the their ability to impregnate cows.
Even though the number of cows that can produce the quality of milk we need to see real improvement in reproductive rates is low, the management of selling open females so quickly has resulted in creating cows that do have a calf every 14 months. However if every cow had access to a high fertile bull with high quality semen, 95% or more of our cows would calve every 12 months. That’s a lot of unrealized potential income.
So what do I mean by a high fertile bull? He is a bull that produces 2-5 billion sperm cells in each cc of seminal fluid. He never runs out of semen. 85-90% of those live cells are moving vigorously to the target to be fertilized. Only 8% or less of those cells are considered (primary or secondary) abnormal. This is a bull that will get 80% of the cows he services pregnant in the first 21 days of the breeding season. That certainly lessens the work he needs to do in the next 21 days.
The standards presented below represent 30 years of research collected by James Drayson at Big Sky Genetics. His book ‘Herd Bull Fertility’ is a must for the serious minded producer, veterinarian or any person who wants to understand the mechanics of high quality germ plasma. The numbers for the first two headings – testicle length and circumference are not exactly the same as what you’ll see in the book and the reason for that is Mr. Dryson’s research was done on conventionally fed cattle. I have measured at least a thousand grass-fed bulls and even the superior ones did not have the testicle length and circumference that Dryson’s grain fed bulls did. I believe his semen test numbers to be accurate for performance classification regardless of diet. The superior bulls that I have worked with met his data for quality, quantity and motility as optimal breeders. The book “Herd Bull Fertility” is available on http://www.bovineengineering.com or by contacting me at firstname.lastname@example.org or 501 454 3252.