Early weaning technology made a significant impact on the swine industry in the early '80s. It was a procedure to improve pig health and provide dramatic advances in performance.
Coupled with improved diets and multi-site production, early weaning and segregated early weaning changed the way pigs were reared worldwide.
In addition to the disease application of early weaning, the more rapid turnover of farrowing crates improves pigs/crate/year. Progress in litters/sow/year and pigs/sow/year was also anticipated.
Producers and veterinarians soon recognized, however, that early weaning could adversely affect wean-to-service intervals, farrowing rate and litter size.
Also, early weaned nursery pigs require more costly diets, a higher level of management and some changes in the environment.
With increased contract production and wean-to-finish barns, there could be some disadvantages to smaller, early weaned pigs. Recent studies suggest smaller weaned pigs may be at a disadvantage for mortality and performance through finishing.
The value of early weaning is being questioned, especially if reproductive performance is declining. Would litter size improve if lactation length were longer? Could we boost farrowing rate at the same time?
The two case reports that follow will attempt to answer those questions by reviewing retrospective data and changes in weaning age.
It is important when doing this analysis to try and predict all the possible biases in the data. These could include sows that recycle, sows with long wean-to-service intervals, parity differences among the lactation length categories, genetic differences and changes in nutrition.
As long as there is good distribution of the lactation lengths for the entire time period under review, most of these potential biases should have a minimal impact on the evaluation. Total born was analyzed due to the potential for other influences on born alive. Sows that recycled after breeding were excluded from the dataset. The lactation length data was reviewed individually and then grouped as it best fit for this review.
In 2001, this 1,600-sow herd had an average weaning age of 15 days, which has gradually increased to 18.2 days.
A PigCHAMP cohort analysis (grouped by previous service date) for the first eight months of 2001 showed an average lactation length of 14.5 days and total born of 11.1 pigs/litter. The same time period in 2003 showed 17 days lactation length and 11.3 total born.
This difference doesn't look too dramatic. However, the report includes total born data from Parity 1 gilts. Repeat breeders are also included. When the analysis was made in more detail, including servicing of non-repeat sows from 9/01/00 to 08/01/03, there appears to be some differences between the two lactation lengths.
There were 1,435 sows with a 7-13 day lactation length that had 10.91 pigs born/litter. In comparison, 6,178 sows with a 14-20 day lactation length had 11.49 pigs born/litter. There were also 225 sows with 21-24 lactation days that had 12.0 pigs born/litter.
Farrowing rate for 5,045 sows with a 10-16 day lactation length was 81%, while 3,748 sows with a lactation length of 17-22 days had an 85% farrowing rate.
This 880-sow herd is a different genetic line than the first case. The herd had a 14-day average weaning age in 2000 and 17.2 average weaning age in 2003. The same service dates were reviewed as in the first case study. The previous lactation length of 10-17 days resulted in 2,749 litters with a total born of 11.88 pigs. When the lactation lengths of 18-25 days were summarized, the total born increased to 12.61 pigs. Interestingly, the farrowing rates were the same as those in the first herd. For a lactation length of 10-16 days (2,622 sows), the farrowing rate was 81%, and for 17-21 days (1,384 sows), the farrowing rate was 85%.
Thus, both of these herds showed some improvement in total born and farrowing rate when lactation length increased.
There are many more factors that must be considered when making the decision to increase wean age or lactation length.
Although it is difficult to collect on-farm data for all aspects of production impacted by weaning age, these cases demonstrate some of the analyses that may be helpful in making weaning age decisions.
Remember that it is important to review the records of all phases of production before making the decision. Just because a change is right for one operation doesn't necessarily validate it for yours.