P. Medel

Processed cereals in diets for early-weaned piglets

Two trials were carried out to study the influence of cereal processing in diets for early-weaned piglets. Six diets were formulated on an alternate base of two cereals: barley or maize, and three types of processing: control (raw), extrusion and micronization according to a factorial arrangement. In Trial 1, 120 male piglets weaned at 23 days and weighing an average of 6.4 kg, were randomly affected by litter in successive blocks and used in a 25-days performance trial. In Trial 2, 18 piglets, three animals per treatment, were used to measure apparent faecal digestibility of dry matter (DMD), organic matter (OMD), energy (ED), crude protein (CPD) and neutral detergent fibre (NDFD). Ileal viscosity, and pH of stomach, caecum and colon were also performed. In Trial 1, piglets fed barley-based diets grew faster than piglets fed diets based on maize (423 versus 404 g/ d; Pa 0.04). Heat processing of the cereal improved daily gain (423 versus 396 g/d, Pa 0.01) and feed conversion ratio (1.18 versus 1.25 g/g, Pa 0.02) with respect to diets based on raw cereal. An interaction between type of cereal and heat processing was observed for the first 2 weeks of the experiment: the improvement in daily gain associated with heat treatment was higher for barley than for maize (13.7 versusˇ4.3%; Pa 0.08). The same occurred for feed efficiency (ˇ14.5 versus 3%; Pa 0.06). No differences were detected between types of processing for growth or feed efficiency. In Trial 2, maize-based diets had higher DMD (0.908 versus 0.871; P < 0.001), OMD (0.921 versus 0.880; P < 0.001), ED (0.905 versus 0.863; P < 0.001), CPD (0.886 versus 0.860; Pa 0.04) and NDFD (0.795 versus 0.708; Pa 0.03), than barley-based diets. Processing of cereals increased digestibility of nutrients but only OMD was improved significantly (0.908 versus 0.886; Pa 0.05). Neither ileal viscosity nor pH of stomach and caecum contents were affected by the experimental treatment. Maize-based diets reduced colon pH compared to barley-based diets (6.18 versus 7.00; P < 0.01). It is concluded that processing of cereals improves performance and OMD of diets for piglets and that this improvement is higher for barley than for maize. # 1999 Elsevier Science B.V. All rights reserved.

Influence of sex and castration of females on growth performance and carcass and meat quality of heavy pigs destined for the dry-cured industry

Crossbred pigs (n = 240) from Pietrain x Large White sires mated to Landrace x Large White dams, with an average age of 100 d (60.5 +/- 2.3 kg of BW), were used to investigate the effects of sex and slaughter weight (SW) on growth performance and on carcass and meat quality characteristics. There were 6 treatments arranged factorially, with 3 classes (intact females, IF; castrated females, CF; and castrated males, CM) and 2 slaughter weights (114 and 122 kg of BW). Each of the 6 combinations of treatments was replicated 4 times, and the experimental unit was a pen with 10 pigs. Castrated males and CF ate more feed, grew faster, and had more carcass backfat depth and fat thickness at the gluteus medius muscle but lower loin yield than IF (P < 0.05). In addition, CF and CM had more intramuscular fat (P < 0.05) and less linoleic acid content in the subcutaneous fat (P < 0.01) than IF. Pigs slaughtered at 122 kg of BW had lower ADG (P < 0.05), decreased G:F (P < 0.05), and more gluteus medius fat than pigs slaughtered at 114 kg of BW (P < 0.05). It was concluded that CF and CM had similar productive performance and meat quality characteristics when slaughtered at the same age, and that castration of females improved ADG and increased weight and fat content of primal cuts with respect to IF. Therefore, castration of females is recommended in pigs destined for the dry-cured industry because of the beneficial effects on quality of the primal cuts.

Particle size and heat treatment of barley in diets for early-weaned piglets.

One hundred and twenty male piglets weaned at 20 days and weighing 5.7±1.0 kg were used in a 28-day trial to evaluate the effect of dietary particle size and heat treatment of barley on performance and total tract apparent digestibility. There were four dietary treatments: coarsely ground barley (4.5 mm screen); finely ground barley (2.5 mm screen); micronized and then finely ground barley (2.5 mm screen); and finely ground (2.5 mm screen) and then expanded barley. All the diets contained 500 g of barley issued from the same batch/kg. There were six replicates of five piglets per treatment. Total tract apparent digestibility of organic matter (OMD), energy (ED) and crude protein (CPD) were assessed from samples taken at 14 and 28 days from each replicate using chromic oxide as indigestible marker. No differences were found between results associated with screen sizes in the raw barley-based diets. Processing of barley caused an increase in starch gelatinization, a decrease in the proportion of large particles (>1.25 mm) and an increase in the proportion of fine particles (<0.16 mm; p<0.05), as compared with unprocessed barley. Piglets fed processed barley-based diets grew faster than piglets fed raw barley-based diets only in the first 14 days of experiment (232 vs. 204 g per day; p=0.04). Feed conversion was not modified by barley processing. Processed barley-based diets showed higher values for OMD, ED and CPD than raw barley-based diets, but only the difference for OMD approached significance (0.817 vs. 0.784; p=0.07). It is concluded that processing of barley improved piglet performance in the first 14 days post-weaning, and that no differences exist between processing techniques or grinding size of barley for any of the traits studied.

The effects of gender and castration of females on performance and carcass and meat quality of heavy pigs destined to the dry-cured industry

The effects of gender and castration of females (IF, intact females; CF, castrated females; CM, castrated males) on performance and carcass and meat quality were studied in crossbred pigs (Landrace×Large White dams×Duroc sires) slaughtered at 119.2 (experiment 1) or 131.6 (experiment 2) kg body weight. Intact females had better feed conversion and less carcass fat than CF and CM. Trimmed shoulder yield was higher for CM than for CF with IF being intermediate. Primal cut yield and meat quality were similar for all treatments. Proportion of linoleic acid in backfat was lower in CF than in IF or CM and the differences were significant when pigs were slaughtered at 131.6kg. The higher fat content and the fatty acid profile favor the use of castrated females and males over intact females for the production of heavy pigs destined to the dry-cured industry.

Productive performance, carcass and meat quality of intact and castrated gilts slaughtered at 106 or 122 kg BW.

A total of 200 (Landrace × Large White dam × Pietrain × Large White sire) gilts of 50 ± 3 days of age (23.3 ± 1.47 kg BW) were used to investigate the effects of castration (intact gilt, IG v. castrated gilt, CG) and slaughter weight (SW; 106 v. 122 kg BW) on productive performance, carcass and meat quality. Four treatments were arranged factorially and five replicates of 10 pigs each per treatment. Half of the gilts were ovariectomized at 58 days of age (8 days after the beginning of the trial at 29.8 ± 1.64 kg BW), whereas the other half remained intact. The pigs were slaughtered at 106 or 122 kg BW. Meat samples were taken at Musculus longissimus thoracis at the level of the last rib and subcutaneous fat samples were taken at the tail insertion. For the entire experimental period, CG had higher (P < 0.05) BW gain and higher (P < 0.001) backfat and Musculus gluteus medius fat thickness than IG. However, IG had higher (P < 0.05) loin and trimmed primal cut yields than CG. Meat quality was similar for IG and CG but the proportion of linoleic acid in subcutaneous fat was higher (P < 0.001) for IG. Pigs slaughtered at 122 kg BW had higher (P < 0.001) feed intake and poorer feed efficiency than pigs slaughtered at 106 kg BW. An increase in SW improved (P < 0.001) carcass yield but decreased (P < 0.05) trimmed primal cut yield. Meat from pigs slaughtered at the heavier BW was redder (a*; P < 0.001) and had more (P < 0.01) intramuscular fat and less thawing (P < 0.05) and cooking (P < 0.10) loss than meat from pigs slaughtered at the lighter BW. In addition, pigs slaughtered at 122 kg BW had less (P < 0.01) linoleic acid content in subcutaneous fat than pigs slaughtered at 106 kg BW. Castration of gilts and slaughtering at heavier BW are useful practices for the production of heavy pigs destined to the dry-cured industry in which a certain amount of fat in the carcass is required. In contrast, when the carcasses are destined to fresh meat production, IG slaughtered at 106 kg BW is a more efficient alternative.