Recently, Zoetis was granted a label extension for the use of IMPROVEST for the temporary suppression of estrus in market gilts. By suppressing estrus and therefore reducing ovarian development, gilts significantly increase the amount of feed consumption post second dose of IMPROVEST, improving group uniformity compared to conventional or non-treated gilts¹. The research body of work continues to demonstrate a consistent improvement in weight gain resulting in heavier carcass and primal weights as well as enhanced belly yields and intramuscular fats.

Zoetis scientists presented two papers at the annual 2022 Midwest Animal Society of Animal Science meeting in Omaha. The objective of the first paper was to assess optimal market timing post-second dose of IMPROVEST for production measurements.

This experiment indicated that:

1. In the first cut of marketed females, IMPROVEST and Control females had similar weights for the 19 and 25 day post-second dose treatments, but IMPROVEST females were heavier than Control females at the 32 and 39 day post-second dose treatments.
2. In the final cut of marketed females (Table 1), IMPROVEST females were heavier than Control females for the day 39, 46 and 60 post-second dose treatments (7.2, 3.7, and 6.8 lbs, respectively).
3. For the first marketing group, feed-to-gain ratio (when measured from day 81 to marketing) was similar between IMPROVEST and Control females at 18-, 25- and 32-days post-second dose; feed efficiently was worse for first cut gilts at 39 days.
4. As expected, the feed efficiency was impaired with the longer duration post-second dose for both marketing groups. By delaying the marketing one week post-second dose, feed efficiency was adversely affected by about four percent per week for both IMPROVEST-treated gilts and Control females.

Conclusion: IMPROVEST gilts should be marketed between 25 and 46 days post-second dose to optimize feed efficiency ratio.

Research summary: IMPROVEST administration timing impacts carcass characteristic outcomes in gilts

The second paper was to assess optimal market timing post-second dose of IMPROVEST for carcass characteristics as a companion paper to the previous mentioned study.

This experiment indicated that:

1. Hot carcass weight (1^st Cut = 2.3 lbs: 2^nd Cut = 4.7 lbs), backfat (1^st Cut-=0.04 inch; 2^nd Cut = 0.07 inch) and belly depth (1^st Cut=0.03 inch; 2^nd Cut=0.05 inch) was greater for the IMPROVEST females in both the first and final marketing events.
2. Loin depth (0.037 inch) and belly weights (0.5 lbs) were greater in final cut IMPROVEST females compared to Controls females.
3. Calculated percent lean was reduced (1^st Cut = 0.6%; 2^nd Cut =1.0%) in IMPROVEST females for both marketing events due to the increase in backfat.
4. The time period post-second dose to market does not appear to have tangible impacts on carcass quality.
5. IMPROVEST improved pass rate by 22.3% when considering industry standard thresholds for premium markets (color score = 3 or 4; marbling = 2 or greater; fat firmness = 2 or greater).

Conclusion: The reduction in cyclicity of the gilts in this study by use of IMPROVEST resulted in improved growth weights and therefore market weight compared to Control gilts in addition to supporting improved carcass quality attributes that improved pass rate measurements.

Recommended use program

Based on the results of these two studies as well as the more extensive published meta-analysis, the use of IMPROVEST in gilts is a very viable technology for the use in commercial pork production. These results clearly demonstrate the critical relationship of balancing the projected value of increased carcass weights and value and group uniformity compared to feed efficiency.

According to label directions, IMPROVEST is administered as a two-dose injection regimen. The first dose should be administered no earlier than nine weeks of age; the second dose should be administered at least four weeks after the first dose.

Practical implication: To maximize IMPROVEST outcomes, it is recommended the following dose/marketing timing:

• Dose 1, 8 weeks prior to the first marketing cut
• Dose 2, 4 weeks prior to the first marketing cut

IMPORTANT SAFETY INFORMATION: Pregnant women should not administer IMPROVEST. Women of childbearing age should exercise extreme caution when administering this product. Exercise special care to prevent accidental self-injection because of negative effects on reproductive physiology in both men and women. However, there is no risk associated with consuming pork from animals administered this product. Do not use IMPROVEST in male pigs or gilts intended for breeding, or in barrows, cull boars or sows. See full Prescribing Information: https://www.zoetisus.com/improvestpi