Chute and breeding box offer no difference in pregnancy rates

Published on Feb. 22, 2020

Reproductive efficiency is a key component to profitability in any beef cowherd. With volatile markets and unpredictable weather patterns, a producer in today’s industry must be able to mitigate as many risks as possible. 

            Innovative technologies such as record keeping systems, genomic testing and assisted reproductive techniques have provided producers with more tools than ever before to make profit driven management decisions. 

            As beneficial as some management tools seem though, not all have been verified through scientific testing. Artificial insemination (AI) has been one of the greatest advancements in the beef cattle industry. 

            Availability of superior genetics allows producers to greatly increase the value of their calf crops without making major investments. One downfall to AI though is the amount of training and precision needed to obtain economically acceptable pregnancy rates. Even once all human error variables are removed, success of AI programs are still dependent on the physiology of the cattle themselves. 

            In order to fully optimize the use of AI, cattle must be in an adequate state of health and body condition. Along with these production characteristics, cattle must also exhibit low levels of stress just prior to ovulation. 

Breeding box

Stress has been shown to greatly reduce the effectiveness of AI in beef cows of both Bos taurus and Bos indicus descent. Stress often delays ovulation resulting in inefficient synchronization protocols and reduced pregnancy rates. These findings ultimately led to the creation of the “breeding box.” 

The breeding box was first designed in 1969 by R. A. Parson and W. N. Helphinstine to reduce handling stress of cattle during artificial insemination. The box was solid sided with a solid gate and overhead roof allowing for minimal light infiltration and limited vision inside. Because the animal is unable to see and is not completely restrained, it was theorized that it would be calmer during breeding, resulting in higher pregnancy rates. 

This concept has lasted throughout the past 50 years and many producers today choose to incorporate a breeding box in their operation. As beneficial as a breeding box may seem, limited scientific data is available to prove if the breeding box truly increases pregnancy rates or decreases physiological stress. 

Studies

 A collaborative study conducted between Tarleton State University in Stephenville, Texas, Virginia Polytechnic Institute and State University in Blacksburg, Va. and R. A. Brown Ranch, Throckmorton, Texas, investigated the effects of both a breeding box and a conventional squeeze chute on beef female physiological stress and pregnancy rates to fixed-time artificial insemination. 

This study utilized 331 Bos taurus females from both the R. A. Brown Ranch and the Virginia Tech experimental cowherd. All females were deemed adequate in terms of age, health and body condition prior to the beginning of the study. Cows and heifers were all estrus synchronized prior to breeding. 

At the day of breeding, females were randomly assigned to be bred in either the breeding box or the squeeze chute. Once restrained, all cattle were assessed for temperament within the restraint device and were evaluated again once the animal was released. Whole blood samples were collected immediately following breeding in order to measure plasma cortisol. 

Cortisol is a hormone produced in the adrenal glands that is a direct product of stress. This hormone is of importance because of its role in delaying the occurrence of ovulation. Thirty days after exposure to AI, all females were examined for pregnancy using ultrasound technologies. 

Results

Results for this study indicated use of either the breeding box or the squeeze chute produced acceptable pregnancy rates. Pregnancy rates between the box and the chute showed no statistical difference with females bred in the box conceiving 57 percent of the time and females bred in the chute conceiving 69 percent of the time. Cortisol levels were almost identical between the box and the chute. 

Although no differences in this study were detected, conclusions can still be made from the data. A lack of difference in pregnancy rate and cortisol indicate from a physiological standpoint, no restraint device offers an advantage over the other. 

This leaves the decision on which restraint to use to be made according to what the producer feels is the safest and most efficient for their operation. 

Although a breeding box may not offer increased pregnancy rates through reduced stress, it does offer advantages in terms of technician comfort and safety. Breeding technicians have much more room to operate when using a box when compared to a chute. 

This often reduces time needed to inseminate each female as well as limits injuries to breeding technicians. Installation of breeding boxes can be costly though when built as separate structures. Breeding boxes also do not allow for Beef Quality Assurance (BQA) guidelines to be followed. Due to the solid sides and lack of restraint of the animal, it is impossible to administer hormone injections correctly while the animal is in the box. 

If a breeding box is installed it should either be a portable device or be permanently placed immediately following a squeeze chute. Restraint in either device is a stressful event for breeding females. In order to reduce stress, emphasis should be put on proper cattle handling techniques prior to breeding. 

Highly temperamental females should also be culled to reduce a herd’s overall temperament. Partial stressing of cattle is inevitable when using AI but reducing overall temperament of a herd can help mitigate this problem.

In conclusion, both a breeding box and a squeeze chute are adequate for use in AI programs.  Producers currently using a breeding box should not abandon this piece of equipment if they feel more comfortable or safe, and producers currently utilizing a squeeze chute should evaluate the cost of installing a breeding box versus the potential returns associated with stress and pregnancy rates. 

This article is courtesy of Russell Carrell, MS and David Roper, PhD. Carrell is a graduate assistant of animal science and forages at Auburn University and Roper is an assistant professor of animal science at Tarleton State University. They can be reached at rcc0057@auburn.edu or droper@tarleton.edu. 

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