By Dr Peter Evans, veterinary consultant
This is a brief report on a data survey done to evaluate whether or not Xmas infertility is common on South African farms. Xmas infertility is defined (for purposes of this article) as poorer reproduction performance as a result of a lack of diligence during the holiday season.Data
A questionnaire was sent to farmers requesting the following information:
• Number of females served on a weekly basis from Week 36 of 2004
(= End of Aug/beginning of September) through to week 17 of 2005.
• Number of females farrowed on a weekly basis from Week 52 of 2004 through to week 33 of 2005.
• Number of piglets born (total = alive + still born + mummies)
The design of the survey was to track weekly farrowing rates in an attempt to plot summer infertility and more especially, identify whether specific weeks were worse than others.
It became apparent that due to farm specific data collection methods, those weekly farrowing rate calculations would be misleading. Thus, a three week rolling average was adopted to “smooth” graphs and allow easier “reading” of results.
Several of the farms’ data were erratic and had to be discarded. The results represent ten farms in four different provinces.
Figure 1 illustrates five of the ten farms three weekly rolling farrowing rate indices. Immediately apparent is the highly erratic rate on individual farms. The darker lines are the average and the trend line.
The index is based on a farms’ own average over the period. E.g. a value of 105% on the graph for a particular week implies that the farrowing rate for that week was 5% above the farms’ 34 week average.
The graph clearly indicates that farms were below average from December through to April. The graph for the other five farms indicated an identical pattern.
Further analysis was done to try and establish whether or not Xmas infertility exists or not. Figure 2 shows the highest index and the lowest index for each week in the study.
Again in this graph the December to April, lower than average farrowing rates, are evident. In addition, weeks 47 to 49 and week two seem to be weeks in which there are tendencies to poorer farrowing rates. (Beginning of school holidays and severe hangovers?)
However, closer examination of the data revealed that from week 47/8 through to week 6/7 few farms are able to get above their average three weekly rolling average. (Figure 4). In week four only one farm was above average, three of the ten were less than 5% below average.
A similar exercise on total born revealed that smaller litters were evident in the same period as farrowing rates dropped, however, the magnitude of the drop (percentage base) was not as large as that seen on farrowing rate.
The data survey clearly illustrates the drop in efficiency seen traditionally through the late summer through to early autumn.
There is also evidence to support the notion that services done in and around Xmas or New Year (Figure 3) tend to be poor on most farms, but not all. Cognisance of this, by committed management and staff, should help reduce the effects of “summer infertility” on farms.
Xmas infertility can be a problem on certain farms.
All the farmers (some who are not clients) who willingly and speedily cooperated to provide the data used. I do hope this information is of value to you and your fellow producers.