Conceiving Bucklings vs. Doelings
Can you influence which gender your doe produces?
Reading Time: 6 minutes
It’s a buck year! It’s a doe year!
Have you ever wondered why some years, some sires — or even some dams — produce more of one gender than others? Can certain management practices favor one over the other — or is it random? Is one more desirable than the other in the goat world?
For many breeders, ratio is everything. Dairy herds prefer doelings to increase production and sell doelings for milk, but bucklings have little value except as herdsires, or pets, and the demand is limited. Dairies celebrate the doe years and struggle to place bucklings. In a meat or pack goat prospect herd, the demand is for males. Meat and pack goat producers celebrate the buck years.
It is indisputable that the sire carries the gender chromosome, so the general assumption is that he is responsible for the gender outcome of his offspring. We would assume that some bucks produce more males and some more females. There is research that validates this (Cory Gellatly, Newcastle University published by Evolutionary Biology). He found that men with more brothers are more likely to have sons, so there can be a genetic predisposition in the sire to produce a single gender — but there was no maternal trend. So why are there does that produce one gender regardless of the sire they are bred to?
Reid Lewis, of Lewis Brothers Ranch in Texas, is one breeder that would like to know! He has raised goats for five years, following in his grandpa’s footsteps — who has had goats all of his life. Reid has 31 does and two bucks — Nigerians and Savannas. One of his first goats was Sugar, a Nigerian Dwarf. Sugar is one of his favorite goats, with excellent conformation and milk lines, and like any breeder, he would like to retain doelings from her. Except she has not offered a single doeling. Thirteen kids, four different bucks, and Reid is 13:0. “I thought it was a coincidence, but she keeps proving me wrong. Hopefully this year, I’ll defy the odds!” Reid has changed bucks every year, and his bucks have 50/50 ratios, as do the other does in his herd. He started reading articles about gender selection and posted a plea for help in a breeder forum to see if gender could be influenced.
There are other scientists that believe that gender determination is far more complex, and the environment of the female influences — and is the possible determinant of — gender selection. Sugar is a prime example. There may be substance to the old wives’ tales of eating bananas for boys and oranges for girls, and that conception of gender is in the water or the phase of the moon. Studies show that gender can be influenced by weather, nutrition, age of breeding pair, and timing of breeding as well. Some of these factors can be managed, to a degree, increasing the likelihood of one gender over another. Except that for every study that predicts selection, there is a contradicting study, bringing the odds back to 50/50. This doesn’t mean that some of these variables wouldn’t influence your outcome.
As is often the case, there are little to no studies on goats, but there are studies on ruminants such as cattle and sheep, as well as other species.
It is indisputable that the sire carries the gender chromosome, so the general assumption is that he is responsible for the gender outcome of his offspring. So why are there does that produce one gender regardless of the sire they are bred to?
One of the most well-known and widely practiced methods of influencing gender at conception was devised by Dr. Landrum Shettles more than 25 years ago. He, and many others, believe that the sperm that carry the Y (male) chromosome are smaller, faster, and more fragile than those that carry the X for females. He posits that breeding as close to ovulation as possible favors male offspring. If breeding takes place before ovulation, the odds are in favor of a female. Cervical mucous is also greatest at ovulation, supporting the male sperm. His studies demonstrated a 75% success rate if the guidelines were followed.
For the average woman, an estrus cycle is 28 days — or a moon cycle — so ovulation and timing of conception could very well be predicted by a moon phase. For a goat, it is 21 days … the moon is no help.
Some studies dispute that male sperm are faster, but show a difference in shape and even size, allowing for semen sorting. Semen sorting is done in a lab and is used in cattle artificial insemination. A 2013 study by the French Institute of Livestock found sorting 90% effective in favoring conception of females.
Other scientists side with wives’ tales — bananas, oranges, and water. They have found that changes in diet in the weeks prior to ovulation change the pH (acidity and alkalinity) of the reproductive tract of the dam, allowing her environment to determine gender by hostile or favorable conditions. Acidic environments favor females; alkaline favors males. A diet high in protein, phosphate, sulfur (and citrus) acidifies the body. Calcium, sodium, potassium, and baking soda alkalize the body. Bananas are high in potassium, and unfiltered water from wells can be high in minerals such as calcium and sulfur, possibly validating the wives’ tales. Further studies of diets high in fats but low in carbohydrates have been shown to favor the conception of males.
What about age? The Trivers-Willard hypothesis suggests that an aged female or female in poor health is more likely to produce female replacements as an evolutionary adaptation to ensure species survival. Interestingly, poor health is associated with acidic conditions in the body, which, from other studies, favors females. From different angles, the studies agree.
Another interesting way diet can influence gender is the practice of “flushing” or increasing feed prior to breeding to boost ovulation, conception, and implantation rates. While studies around flushing demonstrate no effect on conception rates of does in good body condition, the high caloric intake at the time of conception favors males. Combining this with the results of other studies, we might hypothesize further that it is a higher caloric intake of fats and not carbohydrates or proteins, but we can’t be certain, because many of the studies only control one variable — and there are many variables.
In cattle, ranchers often say that a heavily used bull produces more heifers than bull calves. To ensure bull calves, one should increase the ratio of bulls to cows. A study of mountain goats by Sandra Hamel in Tromso, Norway found the opposite … that the more males present, the lower the probability of male offspring.
What about twins and litters of mixed genders? There are studies on this as well, showing that it is not necessarily the conception rate of genders, since there is opportunity for multiple offspring to be conceived, but the success of implantation that determines gender ratio. Like conception, the same variables — nutrition, genetic viability and female reproductive environment – that favor gender, can also favor implantation of one over the other — or be neutral.
While we tend to have an even ratio at Kopf Canyon Ranch, we are definitely curious to track the variables to see if there are trends in our herd — and so is Reid.
Conditions that may favor males:
- Breeding at ovulation
- Doe: Alkaline diet
- Doe: High-fat diet, low carbohydrates
- Doe: High-calorie diet
- Buck to doe ratio
- Age of sire and dam
Conditions that may favor females:
- Breeding prior to ovulation
- Doe: Acidic diet
- Doe: Low-fat diet, high carbohydrates
- Doe: Low-calorie diet
- Buck to doe ratio
- Age of sire and dam
It should be noted that drastic changes in a ruminants’ diet can have unintended consequences and pose a significant health risk. If you choose to alter your management, experiment with caution, ideally under the guidance of a nutritionist or veterinarian. Studies are performed under very controlled conditions. While Reid would love to have a doeling, his preference is healthy kids. Sugar is bred now, due September 23rd 2020. While he is curious, despite his research, Reid hasn’t adjusted his management to try to influence gender, and will not risk Sugar’s health. Will this be the year of the doeling? Will he beat the odds? He promised he would keep us posted and send a picture … Go Team Pink!
Originally published in the September/October 2020 issue of Goat Journal and regularly vetted for accuracy.
