Tips To Enhance Gilt Development

Causes of poor gilt development

“Starting chronologically, one cause of poor gilt development would likely be due to poor selection of gilts at birth,” said Knox. “If you're not selecting the right animals, you may see slow growth during development right up to puberty.

Other causes of poor or slow development:

• Excessive stress - during development, this could occur due to repeated mixing, which results in multiple re-establishments of dominance order
• Crowding - not allowing enough space for the gilts to move and be comfortable
• Limiting feed intake during development – out-of-feed events could be caused by weather or a caretaker emergency. Gilts don't gain that time back, resulting in slower growth and more days open
• Poor air quality and/or poor environment – includes a very dirty environment or high levels of dust or ammonia
• Heat and cold stress – excessive heat requires fans to move the air and various water cooling systems can help. Cold temperatures, especially in the northern hemisphere, can also be a concern and can slow growth due to energy needs for body heat production
• Injury or illness – disease typically takes animals off feed, and illness and diarrhea can add days on to puberty development

Tips for positive gilt development

“Select gilts from the start correctly,” said Knox. “Data suggests that if you select gilts from a dam that is in her second parity or higher, these gilts have better immunity, and they grow better than parity one females. There's nothing wrong with a parity one female; they just don't produce as much milk or antibodies as the higher parity sows.”

Since these are breeding gilts, it’s important to select from a mother that had early puberty because puberty is a moderately heritable trait. Also, select gilts born in a large litter. Even though litter size is lowly heritable, it is still heritable, and the industry is chasing large litter size right now.

“The heaviest pigs in a litter, even in a large litter, tend to grow faster, and we now have a problem with animals getting too heavy for breeding. If this is a problem for the farm, then avoid selecting the heaviest animals and go more towards the medium-sized gilts,” he said.

Ensure adequate pen space. Mixing and moving animals is inevitable, but repeated mixing events can cause stress. The dominant animals will be fine, but not every animal can be dominant.  

“The animals selected from birth should meet targeted weights at weaning,” he explained. “Perhaps you don't need to weigh every single one, but look at them and by 100 days, they should be meeting weight targets, or at least try to recognize animals that are falling behind.”

By 23-24 weeks of age, gilts are ready to start puberty induction and should have reached or be near to reaching their target weight. This is a good time to start measuring or weighing them. Select gilts with a good underline with 14 well-spaced teats and those that respond well to boar exposure in the first, second, third and fourth weeks after starting exposure.

“We want a strong standing estrus and some vulva swelling. If these gilts are growing very fast, you may want to consider starting induction earlier,” he said.

Puberty induction involves gilt exposure to the boar. The boar is the strongest stimulus for advancing puberty in gilts and for detecting estrus. Repeated boar exposure, starting as early as 160 to 170 days – some more tropical regions experience slower growth and will start at 180 to 190 days – will create a slow induction that builds over time.

“Most animals will express puberty by the third week, so the daily exposure works cumulatively,” he noted. “You want an active boar that becomes vocal and gets excited about seeing the gilts, and it’s important to rotate multiple boars. Allow them to breed periodically - that gets them very excited. Providing good quality exposure for the proper amount of time, typically 10 to 15 minutes, should work well to induce puberty.”

Induction does require farm labor to manage the process, and labor can be limited. It’s easy for other tasks to take priority over reproduction.

“I understand that happens, but you don't make up those days and you will add open days to your breeding program,” he said. “So, it’s best to make it a high priority for the team.”

Feeding a developing gilt

“Start by asking an expert – whether it’s a nutritionist, a feed specialist or consultant – to evaluate the gilt diet just to make sure that it’s correct and you have the proper amount of lysine, etc.,” he said.  “During the development period, you want to ensure your developing gilts have access to feed all the time. As opposed to just once daily feeding that may work well for sows, gilts will periodically eat and grow better if they have continuous access to feed.”

Also, ensure there is an adequate number of waters available because water intake drives feed intake. Oftentimes, water is coming from wells, so check water quality to detect if there's an odor or contaminants present.

Check for safe access to feeders. Sometimes feeders get damaged and will have sharp edges. You may notice that animals will have cuts and lesions around their face. Take care of those situations right away by grinding any dangerous edges down.

“I mentioned this earlier, but it’s important – try to anticipate feed issues and prevent out-of-feed events,” he said. “It happens a lot in the winter when workers can’t get to the farm, and it certainly happened often during COVID. If you know the history of feed use and delivery, make sure the feed order is placed on time and when it snows, make sure farm driveways are plowed so feed trucks can get in and out without issue.”

Avoid wet moldy feeds accumulating outside in the bin and in the feed trough itself. Water can easily get in the trough - pigs like to play with their feed - and it can mold which is not good for gilt growth.  

“After pubertal estrus, gilts should continue to receive at least twice daily feed, even when they're moved into stalls,” he explained. “Gilts are still growing. One of the worst things you can do is when they get moved to a stall to prepare for breeding, then they are placed on limited feed before breeding. This is not good for gilts because these animals must keep a growth trajectory; they have to continue to gain weight, even during gestation to reach their mature weight.”  

For heavy gilts, it’s best not to restrict their feed significantly. Dr. Knox suggested limiting feed a little, maybe by 25% or less. He said to try to get them bred at target weight and not let them get too heavy.