Sixty crossbred sows were investigated for the effect of the level of fat reserves in high pregnancy and pre-weaning changes in lipid reserves on reproductive performance of sows and rearing of piglets. At 104 days of pregnancy and at weaning, sows were analysed for body weight, P2 and P4 backfat thickness and M. Longissimus dorsi (MLD) thickness at P4M (Piglog 105). Sows were grouped according to mean backfat thickness (P2 + P4)/2 at 104 days of pregnancy into primiparous (P2 + P4)/2>18 mm (group I), primiparous (P2 + P4)/2.18 mm (group II), multiparous (P2 + P4)/2>20 mm (group I) and multiparous (P2 + P4)/2.20 mm (group II). The body weight of sows from group I was higher than sows from group II at 104 days of pregnancy (P.0.05) and at weaning (P.0.01). As assumed in the experiment, fatness in high pregnant sows (points P2 and P4) was significantly higher in group I than in group II (P.0.01), and the differences between the groups persisted when piglets were weaned (P.0.01). At weaning, sows from group II had a significantly greater P4M thickness compared to sows from group I. The differences in backfat thickness in late-pregnant sows in groups I and II and in the loss of fat reserves during a 21-day lactation had no effect on reproduction results and rearing of piglets. Sows lost body weight to a small extent and fat reserves to a moderate degree; the changes were greater in primiparous than multiparous sows, regardless of the group (I or II).

Weakened growth and development of embryos as well as of fetuses or their organs (IUGR) show a relationship with increasing sow fertility. When aiming to increase birth weight in piglets and reduce within-litter variation in piglet body weight, efforts should be made to maintain a favourable maternal environment (uterus-placenta-embryo). Intrauterine undernutrition can be limited through the hormonal and/or nutritional treatment of pregnant sows. This has an effect on prenatal myogenesis, resulting in better development of skeletal muscles, higher birth weight of piglets, and progression in postnatal growth rate.

The aim of the study was to determine the effect of sows’ condition, being expressed as fat reserve – the mean from two measurements (P2 + P4)/2 on the 104th day of pregnancy (±2 – 3 days) on hematological indicators in blood of PLW x PL sows. Classification of sows into two groups was performed on the basis of lifetime evaluation of backfat thickness in 97 sows (primiparous: multiparous – 30%:70%); group I consisted of the sows with (P2 + P4)/2>20 mm and group II with (P2 + P4)/2≤20 mm. The condition of sows, as expressed by backfat thickness in three dates (late pregnancy, parturition, weaning) amounted to >3,5 for group I and ≤2.5 for group II on a 5-point scale. The examination of hematological indicators was performed on a representative group of 32 randomly chosen sows, 16 animals from each group. Blood for analyses was sampled from the sows on the 104th day of pregnancy and on the 21st day of lactation. Any significant differences between group I and II in respect of morphological indices, excluding significantly higher MCV in sows from group I vs. II on the 21st day of lactation (P≤0.05), were not found. In late pregnancy, significant differences were recorded for the content of ALB and TP (P≤0.05), BUN (P≤0.01), HDL (P≤0.001) and in final stage of lactation – HDL (P≤0.01) (higher in group I vs. II). The mean values of the studied blood indicators of the sows were found within the standards for the species, production group and stage of reproduction cycle, irrespectively of the condition of the females.

The production experiment was conducted on 48 fattener pigs fed complete diets supplemented with the antibiotic flavomycin (group C), the probiotic Bactocell® (Pedicoccus acidilactici, strain MA18/5M) at the amount of 0.01% in the first and second stage of fattening (group E1), and the prebiotic BIO-MOS® (Saccharomyces cerevisiae, strain 1026) at the amount of 0.1% in the first stage of fattening (group E2). Serial sections of the duodenum, jejunum and ileum were prepared post mortem. Haematoxylin and eosin and immunohistochemical (Ki-67, PCNA) staining procedures were performed. The effect of the feed additives on the morphological characteristics and proliferation capacity of small intestinal crypt epithelium varied when mitotic indices in groups were compared. In comparison with group C, the enterocytes were higher in group E2 in the jejunum (P ⪬ 0.01) and smaller in the ileum (P ⪬ 0.01). Administration of the Ki-67 antibody resulted in fewer positive reactions in the jejunum in group E1 than in group C (P ⪬ 0.01). Enterocyte proliferation in crypt epithelium decreased after the administration of the probiotic or the prebiotic vs. the antibiotic, but the absence of significant differences between the groups may suggest that these feed additives have no adverse effect on the mucosal epithelial cells.

The aim of the studies was to determine the effect of addition of feed antibiotic flavomycin (100 mg in 1 kg of 5% premix - group C) or prebiotic BIO-MOS (cell of Saccharomyces cerevisiae yeasts, strain 1026, 0.1% in the first growing period - group E) on production results, blood biochemical parameters, morphometric intestine properties and composition of intestinal microflora in fatteners. During slaughter of 32 crossbred pigs, blood samples were collected and the following biochemical indices were determined. Segments of small intestine were collected and morphometric analysis was carried out. Post-mortem quantitative and qualitative bacteriological tests and quantitative mycological tests on the determination of the contents of small and large intestine were carried out. The comparable results of fattening and slaughter evaluation of pigs in the groups were obtained. Significantly lower HDL (P≤0.01) and higher ALT (P≤0.05) content in blood serum of E fatteners was found as compared to the animals from C group. In group C, as compared to group E, significantly higher (P≤0.01) height of epithelial cells of crypts in duodenum and significantly lower one (P≤0.01) in jejunum was found; the results for ileum were comparable. Application of Saccharomyces cerevisiae yeasts feeding caused a favourable increase of the number of lactic acid bacteria in the contents of intestines and a decrease of the content of bacteria from Enterobacteriaceae family, including Proteus vulgaris and hypha fungi. The employment of BIO-MOS in feeding occurred to be favourable from the production and animal health point of view and seems to be a suitable alternative to feed antibiotics.

The study was conducted on a total of 95 Polish Large White, Polish Landrace, Line 990, Pietrain and Duroc gilts fed the same feed. The effect of breed was studied on the intramuscular fat content of longissimus dorsi muscle, its cholesterol, phospholipid and triglyceride levels, and fatty acid profile.The breed effect on the content of lipid components of the muscle was found significant. The composition of intramuscular fat of maternal breeds, i.e. Polish Large White and Polish Landrace, was closest to the consumers' dietetic requirements, however in case of a low muscle level of intramuscular fat. The lipid composition in gilts of synthetic Line 990 was most similar to that found in Duroc gilts.