Selection, Development and Management of Replacement Gilts

Replacement gilts are an important piece of the puzzle for the future productivity of the sow herd, but despite their importance, they often receive low priority. To ensure a successful sow replacement plan, optimal physical development, proper selection, immunity building, pre-breeding preparation and puberty stimulation are all essential for the herd’s reproductive success. Consequently, the conditions in which we raise gilts, including their environment and management, should reflect their high value. 

Optimizing Gilt Selection: Key Factors from Birth to Weaning 

Effective gilt selection begins at birth. Gilts with higher birthweights (>1.3 kg) tend to remain longer in the sow herd compared to lighter gilts, that have higher removal rates due to anestrus and produce fewer pigs over multiple parities. Additionally, gilts from male-dominated litters often underperform later due to higher androgen exposure in utero, leading to masculinization and reduced reproductive performance. 

Colostrum intake may influence ovarian and uterine development, resulting in increased puberty age, reduced lifetime and poor lactation performance. Gilts raised in smaller litters of less than seven piglets are heavier at weaning, reach puberty earlier and have better retention rates over six parities compared to those from larger litters of more than 10 piglets. 

Pre-selection should occur at weaning. Gilts with pre-weaning gains of less than 125 g/day are less likely to be selected for breeding. A weaning age of more than 25 days increases the likelihood of selection, as these gilts tend to have better growth and reproductive outcomes. 

Further Selection of Replacement Gilts 

Proper selection of replacement gilts should be based on their predicted genetic reproductive ability and phenotypic traits. As litter size and growth rates increase until the third or fourth parity, longevity and lifetime reproductive performance become highly important for the financial success of the system. Many sows are removed between the first and second parity due to reproductive failure, lameness or other health issues, making initial gilt selection critical for a solid herd foundation. 

Often, “marginal” gilts are selected to meet short-term breeding targets, but these gilts are frequently removed early, negatively impacting herd performance and leading to higher losses in the nursery and beyond. Slow-growing animals, gilts with poor health, ruptures, abnormal anus and vulva, locomotion problems, bent backs, leg and claw defects and weak pasterns should be excluded from the gilt pool. Detailed instructions for evaluating legs and claws can be found in the Zinpro® Gilt Selection Guide. 

Housing, Nutrition, Health and Acclimatization Management 

Several factors, including genetics, nutrition, health and management, influence a gilt’s ability to remain in the herd long-term. Optimal growing conditions—such as appropriate stocking density, feeder space, water supply and environmental management—must be maintained from birth to first breeding. 

When gilts are purchased from outside sources, an 8-12-week quarantine is typically required to acclimatize them to the farm’s health conditions and protect the farm from external threats. The quarantine unit should be completely separate from the reproduction unit and ideally operate on an “All-In, All-Out” system (pigs are kept together, matched by age, weight, production stage, condition throughout their lifecycle) by barn or house to break the infection chain. 

Additional Tips to Properly Manage Gilts 

Before Receiving Gilts: 

• Ensure pens are clean, properly disinfected and dried. 

• Check that drinkers are functioning well by cleaning and measuring their yield. 

• Provide an environment similar to the sow farm to help prepare gilts for the transition. 

• Avoid overstocking and stress as they move into the breeding environment. 

Receiving Gilts: 

• Minimize stress when moving gilts into pens. 

• Ensure walkways are short, non-slippery and avoid rushing the animals. 

• Maintain an ambient temperature of at least 20°C (68°F) upon arrival, provide heating if necessary and ensure adequate floor space. 

• Have fresh feed available upon gilt arrival. 

• To reduce stress during mixing, provide straw, grass or alfalfa hay if possible. 

• Collaborate with a veterinarian to decide on treatment for any lame animals due to transportation. 

• Establish a vaccination program to boost immunity and help the new gilts adapt to the farm’s health conditions. 

Cleanliness 

• Remove feces at least once daily to keep pens dry and prevent claw lesions and lameness.  

• Minimize mixing gilts into new groups to reduce stress and fights.  

• Engage with gilts beyond routine tasks. 

Light 

• Provide white, fluorescent light at a minimum of 250 lux for 10-12 hours per day. 

Air Quality 

• Maintain good air quality with low levels of ammonia and dust. Carbon monoxide should not exceed 50 ppm. Keep humidity between 50-70%. 

Water Quality 

• Use human drinking water quality where possible. Ensure water quality is good  (Zinpro® H2O Water Analysis Program)  

Floor Design 

• House gilts in pens with a partial slatted floor. The solid part should slope 3% towards the slatted floor, with a level transition. Ensure the concrete is not slippery or broken. Beam width should be 60-80 mm with an open area of 18-20 mm; for individually housed gilts, the beam can be 70-100 mm. 

The selection, development and management of replacement gilts will define the future productivity of the sow herd. By providing the right environment and management practices, we can maximize gilt potential and secure a productive and profitable future for your production system.  

As we continue to refine our strategies and practices, we remain committed to the health and wellbeing of animals, ultimately leading to better outcomes for our business and our customers. 

Are you Ready to Transform the Future of Your Sow Farm? 

With over 53 years of experience in swine production, our experts are ready to help you maximize animal health and productivity, all while helping your business stay profitable.  Contact one of our swine experts today. 

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