CHAPTER 62 Reproductive Health Programs for Beef Herds: Analysis of Records for Assessment of Reproductive Performance
Those operations that emphasize decreased cost of production and the optimization of production efficiency should remain competitive in the years to come. However, certain external factors outside the “farm gate” will continue to have a dramatic effect on how cow and calf producers conduct their business. The continued consolidation in the packer and retail segments, the move from commodity beef production toward branded retail products, and the globalization of world markets will certainly help shape the face of the beef industry. The need for producers to develop record systems that can track individual animals from conception to consumption will be driven by consumer demands for a safe and wholesome product, legislation that mandates country of origin labeling (COOL), and the threat of foreign animal disease outbreaks. It is a certainty that an identification system will become federally mandated in the United States in the near future.
Recent survey data in Mississippi would indicate that over 50% of cow/calf producers do not use individual animal records to make management decisions.1 This same survey suggests that nearly 40% of these producers do not use financial records. Larger operations were more likely to use the information provided by records (both animal and financial) when making decisions compared to smaller operations. However, even in the largest herds (over 500 head), nearly one third did not use animal records in the decision-making process. Although these findings may be surprising, they represent a real opportunity for practitioners to increase their involvement in the overall reproductive management of these operations.
Most indices currently used to evaluate herd performance are directly tied to reproduction efficiency. Measures such as pregnancy rate, calving percentage, calving distribution, and percent calf crop all affect pounds of calf produced per exposed female. If reproductive performance falls below targeted levels, the practitioner is often asked to provide a plan to improve efficiency. This process requires that the producer provide or the practitioner construct adequate herd records to facilitate the evaluation process. This process will ensure that needed changes in herd management can be identified and that cost-effective solutions can be documented and evaluated over time.
The usefulness of available herd information is totally dependent on its accuracy and its relationship to meaningful reproductive performance measures. Data not meeting these criteria are irrelevant and only serve to make the veterinarian’s task more difficult. In those situations in which records are incomplete or inaccurate, the practitioner would be better off taking time to design a system of data collection to fit the operation. This system could be as simple as an index card for each cow. It could also involve a customized spreadsheet or database application or utilize one of the currently available software packages on a laptop or PDA. Regardless of the collection system used, data are only useful if they facilitate decision making.
The minimum data required to begin any analysis2 include factors such as cow identification, age, breed, body condition score, pasture location, and estimated days pregnant, all of which can be captured chuteside as each group of breeding females is processed. Female weights and frame score are also useful parameters to track if those numbers can be conveniently collected.
Pregnancy evaluation should be done as soon as possible after the end of the breeding season. This allows a more accurate dating of the pregnancies and an earlier indication of reproductive performance. Performance of individual breeding groups as well as the whole herd can then be compared to established targets for operations in a particular geographic region.3 This type of reproductive information is critical in evaluating the success of the breeding program.
The bull battery represents the other half of the reproductive equation. Information concerning the day the bulls entered and left the pasture, bull breed and identification, and pasture assignment should also be collected.3 Purchased bulls that have been added to the herd since the last breeding season should have their breeding soundness examination forms, registration papers with EPD values, and health certificates examined by the practitioner. The producer should retain these records at least through the following calving season and preferably for as long as the bull remains in the herd. This information can be very useful when trying to track down the cause of reproductive losses or increased calf morbidity.
Detailed herd surveys can also be used to build an initial database.4 Herd surveys not only give the veterinarian an overview of the operation, but also require the producer to take time and review the production practices currently in use. These surveys come in many formats; they should cover areas such as the animal health program, feeding practices, supplemental feeding, land allocation, grazing and fertilization practices, genetic selection, and physical facilities. Financial information should also be considered. Once accurate information is obtained, the veterinary clinic can act as a central data procession point to compile and analyze individual cow data and overall herd performance.
When evaluating the success of the breeding program, the traditional measure that has been most often used is percent pregnant. Taking the number of animals pregnant in the individual group or herd and dividing it by the number of exposed females will calculate this measure. Although this measure has some value, it gives no insight into important factors such as the length of the breeding season, bull-to-female ratios, grazing conditions, or cow characteristics (age, body condition score [BCS], or frame score) that have an impact on reproductive performance. A more complete analysis of herd performance would enable the veterinarian to judge when individual cows become pregnant and the percentage by each estrous cycle. A complete evaluation allows the practitioner and client to track cow and bull reproductive performance, replacement heifer development, and the herd’s nutritional status.2,3,5,6 This type of analysis leads to a better understanding of production problems, intervention strategies, and lines of communication between the producer and practitioner.
If accurate production records already exist, variations in female reproductive performance can be assessed by cow age, breed, frame score, and body condition score. However, in many cases the first opportunity to access this information occurs at the time of pregnancy examination. Although this evaluation should determine pregnancy status first and foremost, the analysis should also consider the costs involved in getting cows pregnant and the value of the weaned calf. Cost centers such as the nutritional program, heifer replacement, and grazing costs can then be related to overall profitability. Also, the timing of herd management events should be evaluated and clearly defined.3
Once all data are collected, this information can be summarized in tabular form as a starting point for the herd analysis (Table 62-1). As this is done, individual group and herd factors that affect reproductive performance will begin to emerge. The fall-calving herd profiled in Table 62-1 shows excellent reproductive performance across all age groups. With the exception of the expected decrease in performance of the oldest set of cows, there was no real difference in percent pregnant, average days pregnant, or body condition score. Typically, the 3-year-old females are the most difficult group to get rebred because they are nursing their first calf. In our experience, it is not unusual to see the pregnancy rate in this group of females drop 5% to 10% below the herd average, while taking 10 to 14 days longer to conceive. Because of the capital invested in the replacement heifer program, it is critical that these young females be monitored and managed to ensure acceptable reproductive performance through their first two breeding seasons.
Nutritional management can have a dramatic impact on reproductive performance.7 Also, the supplemental feeding program typically represents the largest cash cost associated with the cow/calf operation. The nutritional status of the herd can be monitored by using a body condition scoring system to evaluate the success of the feeding program.2 By dividing the herd into groups based on body condition, the practitioner can evaluate reproductive performance and communicate those findings to the producer. Table 62-2 details the relationship for another fall-calving herd. This particular operation was successful in managing the forage base and supplemental feeding program so that less than 10% of the herd was in borderline condition (BCS = 4) at the time of pregnancy examination. Because of the expense associated with feeding the cow herd and the critical role that nutrition plays in productivity, it is critical that this relationship be evaluated on an annual basis.
Calving histograms can be used to further define the conception pattern of the herd and the expected calving distribution.5,6 The histogram shows the percentage of females bred in each 21-day period (Fig. 62-1). This process should be done for the entire herd and then broken down into specific breeds, ages, body condition scores, or pasture locations, as deemed necessary by the practitioner. Reasonable targets for mature cows (4–8 years old), using a limited breeding season (45–75 days) include having 60% of the females conceive in the first 21-day period and less than 10% open. These targets will vary for different female groups and environmental conditions.