Introduction

The use of A.I. on swine farms in the U.S. has increased exponentially over the past 10 years. As a result, the influence of breeding technicians on the overall fertility of a breeding herd has also increased. While differences in farrowing rates and number of pigs born alive from sow whose mating were supervised by different technicians has been well documented (Flowers, 1998), few studies have been designed to address possible reasons for these differences in an objective manner. It is possible that a portion of the variation commonly observed among the performance of breeding technicians is related to the number of consecutive matings that they are required to administer during daily breeding periods. It is not uncommon for breeding technicians on swine operations to supervise the matings of 50 or more sows over a 4 to 5 hour period. Since the mechanics of performing an A.I. mating are repetitive, it is reasonable to speculate that the precision with which they are performed probably diminishes with time. If this does occur, then a simultaneous decrease in the reproductive performance of sows would also be expected. Consequently, the objective of this study was to determine the relationships among daily breeding demands, individual breeding technicians and sow fertility.

Materials and Methods

Two studies were conducted on a commercial swine operation whose weekly breeding target was between 220 and 250 sows. In the first study, 5 breeding technicians were randomly assigned to breed between 5 and 50 females per day for 26 weeks. Breeding assignments were made in such a way that sow parity, past reproductive performance of sows and boar fertility were similar among all technicians. All technicians followed a mating regimen that consisted of one insemination each day of estrus beginning at first detected estrus. For sows that were bred more than once, technicians were required to breed them in the same chronological order each day. Farrowing rate and number of pigs born alive were evaluated for each technician using analysis of variance procedures. In the second study, all procedures were idenitical were identical to the first study except technicians were not allowed to breed more than 15 females consecutively without taking a 30 to 45 minute rest period.

Results and Discussion

Table 1 contains the average farrowing rate and numbers of pigs born alive from sows whose matings were performed by the 5 breeding technicians during the first study. The difference between the best and worst techicians in terms of farrowing rate and litter size were 21% and 2.6 pigs, respectively. Table 2 compares the farrowing rate of the first 15 sows to the the remainder of the sows that each of the 5 technicians bred on any given day during the study.

^a,b,cmeans within the same column with different superscripts are different (p < .05).

* different from first 15 sows bred (p < .05)

For technicians 1, 3, 4 and 5, the farrowing rate of first 15 sows was greater (p = .03) than the farrowing rate of the remainder of the sows. Similar trends were also observed for numbers of pigs born alive (data not shown). It is interesting to note that the technicians 1, 3 and 5 had the lowest, overall average farrowing rate also had the largest differences in farrowing rates between the first 15 and the remainder of the sows they bred. Moreover, the farrowing rates from the first 15 sows bred by 4 of the 5 technicians were statistically similar (p = .4). One interpretation of these data is that there is a tendency for farrowing rates and number of pigs born alive to decrease in sows bred late compared to those bred early in a daily breeding period in some, but not all breeding technicians. In addition, in this particular study, the majority of the difference in the overall farrowing rates of sows supervised by each of the technicians could be attributed to the farrowing rates of the sows that each individual bred late in the mating sequence.

Results from the second study in which breeding technicians were given a rest period after breeding 20 sows consecutively are shown in Table 3. There were no differences in farrowing rate or litter size (data not shown) between the sows bred early and late in each daily breeding period.

Summary

In summary, situations in which breeding technicians are required to breed large number of animals consecutively without rest probably are not conducive for optimal reproductive performance.