The objective of gilt management should be to have Achieve gilt puberty as young as possible and then subsequently be prolific regularly for as long as required. The main objective of gilt management is to produce long-lived and prolific breeding females, ie. minimis non-productive days (NPD) and maximising lifetime productivity.

 

 

This requires that pubertal gilt working as soon as possible after arrival on the farm. This does not necessarily mean that screams should be bred at a young age, only that they start cycling when young. Interestingly, it has been suggested that screams that Achieve an early puberty have better long-term fertility. The decision on when to wide gilt (in terms of age, weight, backfat depth, estrus number) is a separate issue and depends on the farm's management. The ability to meet breeding targets requires a predictable supply of ready-gilt service which is best got by having gilt Achieve an early puberty. If the date of puberty in known, the occurrence of subsequent estrous periods can be predicted and-if necessary-hormonally manipulated to fit the breeding schedule.

 

Boar exposure is the most common practice for inducing early puberty. However, it is important to understand the difference between estrus stimulation and estrus detection. Adequate stimulation requires direct physical contact while detection may only need fenceline contact (although direct physical contact is better). If the efficacy of boar exposure has been questioned, it is important to evaluate Whether the rules are being followed or boar contact. The rules for appropriate boar exposure are:

 

1. Gilt must be old enough, the usual advice is at least 160 days of age although more recent evidence suggests that 180 days may be better with modern gilt (Figure 1). Younger gilt are physiologically too immature to respond to boar contact at younger ages.

 

2. Boars must be old enough (ie. at least 10 months of age) because younger boars do not produce enough pheromones to stimulate gilt. The pheromones are produced in the submaxillary gland Salivary gland and this does not reach adult size until at least 10 months of age.

 

3. Gilt should be in physical contact, in the pen with the boar, for at least 15 minutes per day. Fence Line contact may have some effect, but full contact is much better (Table 1).

 

4. Move gilt to the boar, not vice versa. Taking the gilt to the boar will work, but taking gilt to the boar works better. However, if working with large groups of screaming it is easier to take the gilt to the boar pen but remember to have at least 1 per 12 gilt boar.