Southern Alberta Beef Review

Dr. Joseph M. Stookey
Department of Herd Medicine and Theriogenology, Western College of Veterinary Medicine,
University of Saskatchewan, Saskatoon, SK

I have always believed that we (the people working within the industry) have a responsibility to society and to our animals to identify the procedures that cause the least amount of pain and the least amount of set back to the animal. Once the ideal procedure has been identified we should try to move the industry towards that ideal. However, as a researcher I do not believe we should be investigating the relative impact of various dehorning techniques, when we could easily render them all unnecessary. We already know that the least painful procedure and the one that causes the least set back in growth is to remove horns by genetically selecting for polledness. In cattle, horns are inherited as an autosomal recessive gene, polledness being dominant. In one breeding season, a producer can take a herd of horned cows and breed them to a polled bull (homozygous for the polled condition ) and have an entire polled calf crop.

You might ask, "Why should we worry about horns, maybe we should leave them on and not dehorn cattle?" When horns are left on feedlot cattle, the amount of bruised trim from the carcasses has been reported to be twice that from an equivalent hornless group. The industry's desire to produce a consistently high quality product is compromised by allowing cattle to enter our feedlots with horns. If we dehorn cattle upon arrival at the feedlot, studies have shown the set back in gain can be detected for up to 106 days post dehorning. The bruising and dehorning studies suggest that horns should be removed sometime before cattle reach the feedlot. This concept is reinforced, in many locations, by assessing a horn tax against cattle that are sold with horns. Even for breeding stock, keeping the horns on the cattle comes at a price. Horns are used by cattle in competitive situations. It is difficult to imagine even an extensive range system where dominant cattle with horns would not use them against lower ranking cattle. Certainly, cattle can exert their dominance within the herd using threatening postures and not all encounters are settled through physical contact, but any producer knows that on occasion the head of one cow will meet the hide of another. If cattle have horns, it makes every competitive encounter at the feed bunk, hay bale, shade tree, water trough, etc. potentially more dangerous for animals within the herd.

You might think that cattle (especially cows) need horns to defend themselves and their offspring from predation in certain regions of the country. A very interesting study conducted on African hoofed species belonging to the scientific family Bovidae (meaning "hollowed horned ruminants", in which cattle belong) has shown that predation by lions, leopards, hyenas, wild dogs, jackals, etc. is no higher or lower in species where females have horns compared to species where females do not have horns. In fact, the hunting and attack strategy of predators is no different if the prey is horned or hornless. In addition, most Bovidae avoid predation by flight or concealment and not by defense. Out of the 120 species of animals within the family Bovidae (which includes everything from bison and giraffe to oryx and wildebeest), roughly 80 species have horns in both males and females. In the other 40 species, only males have horns. If horns evolved as weapons that were necessary to defend self and offspring then it would be advantageous for all the females across all Bovidae species to have horns. The fact that we find males in all the Bovidae species have horns, but not all the females has led scientists to speculate that horns (plus antlers in deer, elk, and moose) evolved not as a form of defense against predation, but as displays and weapons for males to use against other males in competition to gain access to females.

If horns are not important for protection against predation and are used by males in male-male competition, then why do females, such as cows, have horns? This is a tougher question and certainly horns can be used as weapons for defense, but some scientists speculate that horns on females may serve another purpose. One of the main differences between species where both males and females have horns compared to species where only males have horns is found in the social structure of the herd. Some species form herds where the dominant males are year long residents and such species tend to have both horned males and females (like cattle and bison). Some species form separate female herds where the males show up only at breeding time and in most of these species only the males have horns (like some species of sheep). This pattern has led some scientists to speculate that adult females may use horns to mimic the appearance of the developing horns of young males. Dominant males are therefore reluctant to drive away young males that are developing horns because they look like females. Scientists are speculating that thousands of years ago our female cattle with horns may have been trying, in a sense, to "buy their males calves more time in the herd" before they were driven away by dominant resident males.

Whether horns on female Bovids are really forms of sexual mimicry is speculation, but I tell you all of this so that 1) you can realize that the presence of horns does not seem to have any positive or negative effects on the level of predation and 2) horns probably evolved for males to use in competition and in females as a way to "trick" the old males to leave the young males alone. Either way, horns in beef cattle are the residual effect of thousands of years of evolution and serve little function in today's beef industry where we have eliminated much of the competition between males. Today, cattle function perfectly well without horns in all the environments we keep them.

Are there other reasons we may want to keep horns in beef cattle? Some producers tell me that they prefer certain horned breeds because they are superior to their polled counterparts. Is this true? In 1996, Dr. Goonewardene from Alberta and I collaborated on a project to compare the performance records of horned and polled Charolais and Hereford bulls kept at two ROP test stations, one in Alberta and one in Saskatchewan from 1985 -1993. We had access to the performance records of 578 Charolais bulls (329 horned and 249 polled) and 1,860 Hereford bulls (1182 horned and 678 polled), sufficient numbers to use for comparison.

As shown in Table 1 we found very little difference between the horned and polled bulls in the traits that were measured at the stations. The polled Charolais bulls did carry significantly more backfat than their horned counterparts, but they were not different in average daily gain, adjusted yearling weight or in scrotal circumference. We did find that the polled Hereford bulls in SK had a significantly higher average daily gain compared to the horned bulls and tended to be larger yearlings. Polled Hereford bulls in Alberta also tended to have a greater average daily gain, but the difference was not considered significant. Another encouraging finding was that the ratio of polled bulls at each test station over the time period had gradually increased as the number of horned bulls decreased. In other words, the ability to locate good polled bulls is becoming less of a problem than it had been previously.

Our findings were similar to other reports from various places around the world. A thesis published by Lange in 1989 found no difference between polled and horned German Simmental cattle in growth, carcass yield, carcass composition, health and reproductive performance. Work reported by Frisch and coworkers from Australia in 1980, comparing various beef breeds, showed no difference between horned and polled crossbred lines in live weight, fertility and mortality rates. The dairy industry is not as fortunate as the beef industry in finding acceptable polled sires. Dairy producers will not use a polled sire until it can match the production traits of the horned bulls and the AI centers will not put selection pressure or emphasis on polled lines unless there is a demand for polled bulls. It appears that horned dairy calves will be with us for quite sometime! Since they must dehorn, information on how and when to dehorn is important. The best evidence suggests that the dehorning procedure causes the least setback and stress if performed on dairy calves within the first week of life and which procedure is used makes little difference.

Whether the level of pain an animal experiences is age dependent is still not known, but we do know that the younger the animal at the time of the procedure the quicker the healing process. Therefore we assume the entire procedure is better on the animal if done at an early age.

There is no doubt that superior beef bulls can be found within either the polled or horned population. However, because of the work and handling associated with dehorning, plus the pain, set-back and stress on the animal, I believe beef producers should intentionally select polled bulls. Historically, polled beef bulls may have been inferior, but there is no evidence that overall differences still exist today. There are no data available to support the notion that horned bulls are thicker, hardier and heavier boned, yet some producer continue to make this claim. When I have tested producers and students, using slides of bulls with the heads blocked from view, it is obvious that they are not able to accurately separate horned from polled bulls. I have not tried a similar test in a slaughter plant, but I am confident that the task of identifying which hanging carcasses belong to a horned or polled animal would be impossible.

I believe that from an animal welfare perspective alone, we should be moving towards dehorning beef cattle via genetic selection. Some may claim that because the pain, stress and set back of dehorning is relatively brief, especially if we dehorn young calves, that the issue of dehorning is not a very big welfare concern. Also, because town folks rarely show up to help us with our daily chores it is easy to assume that somehow what we do on the farm and the choices we make are not anyone's concern. This is simply not true. If you raise cattle you are part of the beef industry and the image the industry creates in the minds of the public has been shaped to some extent by the choices made on each operation. Dehorning our beef cattle via genetics is a welfare friendly practice that everyone in the industry should embrace and support.

Table 1. Averages of measured traits for horned and polled bulls at ROP test stations^a.

ROP Test Station	Breed	Class	ADG(kg/day)	Adjusted yearling wt. (kg)	Adjusted scrotal circ. (cm)	Backfat thickness (mm)
Sask.b	Charolais	Horned	1.59 .01	535.5 3.1	32.3 .17	2.37 .06y
		Polled	1.59 .01	523.3 3.1	32.1 .18	2.64 .07x
	Hereford	Horned	1.36 .02 y	452.5 4.5	31.5 .25	5.07 .25
		Polled	1.41 .01 x	472.1 2.6	31.7 .12	4.93 .13
Albertac	Hereford	Horned	1.28 .01	478.2 1.5	34.1 .01	NA
		Polled	1.30 .01	474.5 2.2	34.1 .14	NA

^a Adopted from Stookey and Goonewardene, 1996. Can J. Anim. Sci. 76:1-5.
^b University of Saskatchewan ROP test station data (1985-1992).
^c Innisfail, Alberta, Hereford ROP test station data (1985-1993).
^x,y Means with different letters are significantly different P < 0.05.