The importance of pigs' castration strategy on carbon footprint of feed intake, nitrogen and phosphorus efficiency under different management conditions.

The environmental impact of livestock production is under scrutiny nowadays and is being situated both on a global level and local level. On a global level, the global warming potential (GWP) of meat production is criticised. On a local level, the excretion of nitrogen (N) and phosphorus (P) is of concern as excess nutrients may lead to water eutrophication and soil acidification. The ERA-NET project SuSI evaluated if immunocastration may act as an ecologically, socially and economic more sustainable alternative compared to pork production with surgical castrates (SCs) and boars (BOs). Here, we report the environmental impact of immunocastrates (ICs) vs SC and BO, based on four trials carried out by European SuSi partners. More specifically, we aimed to compare IC with SC and BO in terms of GWP, N and P excretion per kg of pork production and test if this differed between experiments. There was an interaction between trial and sex category (PTrial × Sex category < 0.005) for all environmental sustainability parameters. Surgical castrates performed worse (higher carbon footprint of the feed intake, N and P excretion, lower N and P efficiency) compared to IC and BO, but the size of the effect was trial dependent. Immunocastrates scored intermediate, with mostly no significant differences from BO in most trials, but with significantly better values compared to SC. Over trials, the carbon footprint of the feed intake (land use change inclusive) per kg lean meat gain in the growing-finishing phase was 9-16% lower for IC vs SC and 9-22% lower for BO vs SC. Nitrogen efficiency of IC and BO was 7-10% and 9-14%, respectively, higher compared to SC. Phosphorus efficiency of IC and BO was higher than that of SC by 6-14% and 9-17%, respectively. Per kg of lean meat gain in the growing-finishing phase, IC excreted between 14 and 19% less N and between 14 and 24% less P than SC. For BO, it was between 14 and 27% less N and between 14 and 31% less P than SC. Differences between trials were larger than differences between castration strategies and trial design may have amplified the observed effects. Improving feed efficiency, adapting the feed to the needs of the animal (avoiding excess nutrients) and choosing low-impact ingredients are key for improving the environmental sustainability of pig production. Ending physical castration is another step to attain this goal.

Procedure for determination of glycolytic potential in porcine m. longissimus dorsi.

The aim of this work was primarily to work out a procedure for removal of samples from LD for determination of glycolytic potential in connection with experiments at commercial abattoirs and secondly to determine the correlation between glycolytic potential and ultimate-pH in Danish pigs. Samples of LD were taken immediately after exsanguination and 30 h post mortem. All samples were analysed for the content of glycogen, glucose, glucose-6-phosphate and lactate to be able to calculate the glycolytic potential. The results showed no difference in glycolytic potential in LD irrespective of sampling time. Samples removed after exsanguination contained a higher amount of glycogen and less lactate than samples removed the day after slaughter, where most of the glycogen had been transformed into lactate. These results show that samples for determination of glycolytic potential in LD can be removed the day after slaughter in the chilling room instead of being removed immediately after sticking at the slaughter line, which is less practical and hygienic. There was a significant correlation (-0.61) between glycolytic potential in LD and ultimate pH in LD.

Electrical stimulation of pigs-effect on pH fall, meat quality and Cathepsin B+L activity.

This work was performed to evaluate the effect of electrical stimulation (ES) on pH fall and meat quality of LD and BF in Danish halothane free pigs stunned with CO(2). ES resulted in a significant drop in pH of 0.3 units in both LD and BF and 3 h lairage resulted in 0.1 units lower pH at 20 min post mortem. Lairage time did not affect and did not interact with the effect of ES on any of the measured meat quality parameters. ES did not affect the ultimate pH in LD, BF, SM and SC or internal reflection value in LD. However, ES caused higher internal reflection and drip loss in BF and increased the PSE frequency in LD (2 to 7%) and in BF (2 to 49%). The frequency of PSE areas in the centre of SM was 70% for ES pigs compared to 9% for control pigs. ES and ageing improved the tenderness and reduced the hardness in LD as well as shear force of unaged BF. The effect of ES on tenderness and hardness was approximately half the effect of ageing, but the effect of ES and ageing were additive. ES significantly increased the activities of cathepsin B+L in the myofibrillar fraction, but there were no differences in proteolytic activity in the other fractions. It is concluded that ES improves tenderness in LD and BF, but has a negative effect on the quality of BF and SM. Therefore ES is not an economically attractive alternative for improvement of tenderness in LD compared to ageing in Danish pigs. ©

Effect of early post-mortem cooling on temperature, pH fall and meat quality in pigs.

The aim of this study was to investigate how early cooling of carcasses after slaughter by showering with cold water affected the rate of the pH fall post mortem, protein denaturation and drip loss. Eighty pigs were selected in pairs at debleeding according to sex and farm of origin. All pigs were halothane genotyped and glycolytic potential in LD analysed. One of each pair was cooled 30 min post mortem by showering with 10-12 °C water for 12 min. The control pig was treated normally except for the same delay before batch chilling commenced. The initial pH fall in LD and BF did not depend on the glycolytic potential in LD but at 5 to 6 and 24 hr post mortem pigs with the lowest glycolytic potential had the highest pH. Weight and lean meat content did not affect the cooling curve, i.e. the temperature fall. The results showed that it was possible to reduce the temperature in BF and LD by cooling at slaughter. The maximum difference in temperature between control and cooled carcasses 2hr post mortem was 2 and 1 °C in LD and BF respectively. The lowering of the muscle temperature early post mortem resulted in a reduced rate of the pH fall and a higher pH from 2 to 6 hr in the cooled carcasses. The rate of the pH fall in LD and BF seemed to be independent of temperature at levels above approximately 37 °C, but decreased linearly as the temperature dropped below approximately 37 °C. The cooling procedure used here did not result in a significant reduction in protein denaturation or drip loss, although there was a tendency towards lower drip loss in LD and BF in cooled carcasses.

Comparison of Dehiding versus Scalding and Singeing: Effect on Temperature, pH and Meat Quality in Pigs.

The aim of this work was to investigate the temperature and pH changes taking place at the slaughter line and during the chilling process, and the subsequent effect on meat and eating quality in pig carcasses that had either been scalded and singed or dehided. Both processes were followed by fast chilling. 219 halothane-gene-free Duroc Sire and Landrace-Yorkshire pigs were delivered from three farms and slaughtered over 2 weeks at either a dehiding or a scalding singeing slaughterhouse. Temperature and pH were measured at intervals from exsanguination until 6 hours post mortem. Ultimate pH, internal reflection, drip loss and colour (Minolta) were measured the day after slaughter. Colour (JPCS scale) was evaluated after freezing and thawing, and eating quality was estimated on unaged and aged (4 days at 4°C) m. longissimus dorsi (LD), using a trained taste panel. At the slaughter line the dehided carcasses had an almost constant and lower temperature compared to the scalded and singed carcasses. During chilling there is a shift in temperature curves between treatments, where the scalded carcasses had the lowest muscle temperature in LD and m. biceps femoris (BF) from 2hr post mortem and throughout the measuring period. In spite of the shift in temperature, the dehided carcasses had the highest pH in LD and BF from exsanguination and throughout the measuring period. The rate of pH fall in LD and BF was slowest in the dehided carcasses from exsanguination until 3 and 2hr respectively, post mortem. Dehided carcasses showed a 40% lower drip loss, a darker meat colour and a lower internal reflection in LD and BF compared to scalded and singed carcasses, thus indicating less protein denaturation in dehided carcasses. Scalding and singeing, however, lead to increased tenderness compared to dehiding, and this difference persisted even after ageing for 4 days at 4°C. The differences in toughness may be caused by increased proteolysis by released lysosomal cathepsins.

Muscle metabolic traits, post mortem-pH-decline and meat quality in pigs subjected to regular physical training and spontaneous activity.

Ninety-six female and male pigs were assigned to one of three treatments, 'confined' (C),'trained'(T) or 'free' (F) allowing for different levels of physical activity during the growth interval from 30 to 100kg. Treatment C consisted of individual housing in pens of 2.5 m(2); treatment T of individual housing and regular treadmill training and treatment F of housing in pens of 36 m(2) (40 pigs/pen). In m. biceps femoris (BF), the activity of lactate dehydrogenase (LDH) was decreased between 9 and 12% by training (treatment T vs C). Likewise, in BF from female pigs, training increased the activity of citrate synthase (CS) and of 3-OH-acyl-CoA-dehydrogenase (HAD) by 18 and 21%, respectively. Spontaneous activity (treatment F) reduced the activity of LDH for five muscles between 10 and 16% when compared with treatment C. Around the time of slaughter, glycogenolysis of BF was less for treatment F (6-17%) than for C and T (33-38%). Moreover, in BF from female pigs in treatment F, the initial but not the ultimate pH was increased when compared with treatment C. In comparison to C and T, treatment F improved juiciness in BF from male pigs and increased the amount of salt soluble protein in m. longissimus dorsi.