The Effect of Group Composition and Mineral Supplementation during Rearing on Measures of Cartilage Condition and Bone Mineral Density in Replacement Gilts

Abstract

Simple SummaryThe lifetime performance of commercial sows relies on longevity, which is dependent on good health, particularly, limb health. In many countries, young female pigs (gilts) intended for breeding are often reared with male finisher pigs destined for meat production. However, finisher diets are not designed to meet the needs of developing gilts and may not supply the necessary minerals to support good limb health. Moreover, gilts reared with uncastrated (i.e., entire) male pigs are exposed to high levels of sexual mounting and aggression, which may cause physical damage. This experiment investigated the effect of female-only or mixed-sex rearing with and without supplementary minerals (Copper, Zinc and Manganese) on locomotory ability, cartilage condition and areal bone mineral density (aBMD) of breeding age gilts. The addition of the minerals to the diet resulted in increased aBMD in the humerus bone compared to gilts on the control diet. Rearing gilts in female-only groups reduced the number of cartilage lesions, and there were fewer incidences of elbow cartilage fractures. Overall, both strategies (mineral supplementation and female-only rearing) had benefits for limb health, which could help to improve sow longevity.AbstractLameness is a major cause of poor longevity and poor welfare in replacement gilts. The problem is exacerbated by inappropriate housing and diet during the rearing period. Replacement gilts are often reared with male finisher pigs destined for slaughter. If they are not castrated, they perform high levels of potentially injurious sexual and aggressive behaviour. Furthermore, finisher pig diets are not designed to meet the needs of developing gilts and may not supply the necessary minerals to support good limb health. The objective of this study was to evaluate the effect of supplementing the diet of replacement gilts with copper, zinc and manganese and separating them from males during the rearing period on locomotory ability, bone mineral density and cartilage lesion scores. A 2 × 2 factorial design experiment investigated the effect of female-only or mixed-sex rearing, with or without supplementary minerals (Copper, Zinc and Manganese). In total, 384 maternal line gilts were assigned to 32 pens of 12 and were locomotion scored during the rearing period. A sub-sample (n = 102) of gilts were culled at breeding age and the front right limb was removed at slaughter. Areal bone mineral density (aBMD) was measured using dual energy X-ray absorptiometry, after which the limb was dissected to score the condition of the cartilage. The addition of trace minerals to the diet resulted in increased aBMD in the humerus (P < 0.05) compared to the control diet. Rearing gilts in female-only groups reduced the number of cartilage lesions overall (P < 0.05), and on the humeral condyle (P < 0.05). Rearing replacement gilts in female-only groups and with mineral supplementation had benefits for limb health.

Phenotyping of the Visceral Adipose Tissue Using Dual Energy X-ray Absorptiometry (DXA) and Magnetic Resonance Imaging (MRI) in Pigs

“…In pigs, MRI and DXA (including pure bone mineral analysis [30,31]) are also used for body composition analyses and achieve acceptable results compared to chemical analyses or dissection [32][33][34][35][36]. Our study shows that DXA overestimates VAT compared to MRI and the deviation rises with increasing VAT levels in accordance with other porcine and human studies, where DXA tends to overestimate the amount of fat [33,[37][38][39][40].…”

The effect of group composition and mineral supplementation during rearing on the behavior and welfare of replacement gilts

“…Even though this was after the males had been removed from the groups for slaughter, there may have yet been on-going physical effects on the gilts. Indeed, once the gilts were slaughtered at day 115 (196 d of age), we found more damage to the cartilage on the surface of the humeral condyle joint and trochlear notch, as well as a higher incidence of Osteochondrosis (OCD) in gilts reared in the mixed-sex groups ( Hartnett et al, 2019 ). It is known that pain is associated with OCD ( Frantz, 2006 ) and, thus, it can be assumed that, with overlying biomechanical stress or trauma, this type of damage to the joints could progress to pain and lameness.…”

“…All observations were carried out by one trained observer. Locomotion was assessed using an adapted version of Hartnett et al (2019) ranging from 0 to 5 ( Table 3 ).…”

Lameness in fattening pigs – Mycoplasma hyosynoviae, osteochondropathy and reduced dietary phosphorus level as three influencing factors: A case report

“…and amino acids did not in uence the prevalence of lameness [56]. In another study, mineral supplementation alone did not improve locomotion scores, but in combination with female-only rearing, a signi cant bene cial effect on bone mineralization and joint lesions was shown [57]. Both studies support the multifactorial pathogenesis of osteochondropathy and the lack of evidence for an interaction with mineral de ciency.…”