Production traits of Polish Large White sows kept in breeding herds in the Warmia and Mazury region in the years

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1 Animal Science Papers and Reports vol. 24 (2006) Supplement 1, Institute of Genetics and Animal Breeding, Jastrzębiec, Poland Presented at the Conference Genetic and Breeding Research on Pigs with Special Reference to Indigenous Breeds organized to commemorate the 10 th anniversary of the death of Professor Stefan Alexandrowicz October 2005, Poznań, Poland Production traits of Polish Large White sows kept in breeding herds in the Warmia and Mazury region in the years Wanda Milewska Department of Pig Breeding, University of Warmia and Mazury in Olsztyn, Oczapowskiego 5, Olsztyn, Poland A total of 1337 Polish Large White (PLW) sows from 70 herds were investigated, together with their 4173 litters, i.e pure PLW and 2273 PLW Polish Landrace (PL). Sows were kept in breeding herds in the Warmia and Mazury region in the years and were mated to PLW or to PL boars. Reproductive performance of sows was characterized depending on the size of the herds which were divided into 3 groups: I up to 19 sows, II sows, III 50 or more sows. In the analysed population the mean number of litters delivered by one sow was 3.13 being significantly affected by the size of the herd. Sows from group II had the longest productive life and thus in the whole of their productive lives they delivered on average more litters (3.95; P 0.01) than sows from groups I (2.73) and III (2.77). Also the mean number of piglets in the litters of sows from group II was the highest and amounted to piglets at birth and on day 21. Piglet mortality up to day 21 was low, with the mean of 0.56 piglets (4.49%). It was the lowest in group III and differed (P 0.01) from respective values shown in the remaining groups. Key words: Polish Landrace / Polish Large White / reproduction / sows 103

2 W. Milewska Breeding performance of sows is, apart from fattening and slaughter value, one of the basic criteria taken into consideration in selection work on the improvement of pigs in Poland. Increasing litter size (at birth and on day 21) results in an improved efficiency of pork production. Moreover, increasing litter size offers a potential for more intensive selection for other economically important traits. Hence it is also advisable to carry out annual analyses of reproductive performance traits in pedigree sows [Orzechowska i Mucha 2003]. Efficiency of breeding work in terms of reproduction traits is limited by the low level of heritability and by environmental effects, which may be reduced by optimum feeding and proper zoohygienic conditions throughout the whole period of reproductive life [Buczyński 1988, Kulisiewicz 1988, Tyra i Różycki 2000, Stasiak et al. 2002]. Theoretical estimations indicate that selection response in the improvement of reproductive performance traits may range from l.5 to 2.5% annually, whereas in production traits it may even reach 5% at the assumption that selection for one trait is conducted [Duniec 1984]. The main factor affecting breeding performance of sows is their breed. The most popular and most numerous breeds in Poland, thus having the biggest effect on the pig population performance as a whole, are Polish Large White and Polish Landrace. They account for over 90% of the number of pedigree pigs in Poland and are the primary maternal components in crossing schedules in this country. The aim of the current study was to characterize production traits of Polish Large White sows kept in breeding herds in the Warmia and Mazury region in the years Material and methods The study included a total of 1337 Polish Large White (PLW) sows which were culled after delivering from 1 to 12 litters, and a total of their 4173 litters. Sows were used in 70 breeding herds in the Warmia and Mazury region in the years and were mated to PLW or to Polish Landrace (PL) boars. Thus, among the analysed litters 1900 were purebred (PLW) and 2273 crossbred (PLW PL) litters. The analysis included: individual performance traits: number of teats, standardized daily live weight gain (g), lean content of body (%) and selection index (points); reproduction performance traits: age at first farrowing, age at culling, length of productive life, farrowing interval, number of litters, number of piglets at birth and on day 21, number of males and females in the litter on day 21, and piglet mortality up to day 21. Reproductive performance was characterized as depending on the size of herds, which were divided into three groups: I up to 19 sows, II sows, III 50 or more sows. The characteristic of litters included their origin (from primiparous and multiparous sows), and genotype (purebreds and crossbreds).

3 Genetic and Breeding Research on Pigs with Special Reference to Indigenous Breeds The results were evaluated statistically using the analysis of variance in a oneway non-orthogonal system. Arithmetic means, standard deviations, minimum and maximum values are shown. The significance of differences between the means was verified by Tukey s test. Results and discussion In the years the smallest herds (group I) predominated and accounted for 42.86% of all herds. Those of sows (group II) accounted for 40%, while herds of at least 50 sows (group III) accounted for 17.14% (figures not tabulated). Table 1. Individual performance traits of sows in successive years ( ) Trait Year Years pooled Number of sows Number of of teats Standardized daily live weight gain (g) Mean backfat thickness (mm) Lean meat content of body (%) Selection index (pts) mean B A SD min max mean 595 A 587 A 571 B 594 A SD min max mean b b 9.76 a SD min max mean 57 B 57.1 b 56.8 B 56.7 B 58.1 Aa 57 SD min max mean 122 A 121 A 117 B 121 A 127 A 121 SD min max aa... Within rows means bearing different superscrips differ significantly at: small letters P 0.05; capitals P

4 W. Milewska Table 1 presents the number of teats and live testing results of sows in the years The number of teats ranged from to 14.69, with the mean of This trait shows a significant, but low phenotypic and genetic correlation with reproductive performance traits. Selection for an increased number of teats is thus advisable, since it may contribute to an improved reproduction [Lewczuk et al. 1991]. The number of teats exceeding 14 indicates high breeding value in terms of prolificacy and milk production [Buczyński 1988, Lechowska i Kusz 2003]. Values reaching the maximum (18 teats) suggest a potential for improvement of the trait. Fattening and slaughter indicators in pigs are very important from the economic point of view. In the considered population these live-tested indicators had the following mean values: standardized daily weight gain 588 g, backfat thickness mm and lean content of body 57% (Tab. 1). Mean selection index calculated on the basis of the above mentioned traits was 121 points. It is a very good result, confirming high breeding value of the analysed sows (class I). The maximum value for this trait was 179 points, which shows a potential for further progress in fattening and slaughter performance. However, Johansson and Kennedy [1983] and Eliasson et al. [1991] reported that selection for lean content of body, and thus lower backfat thickness, has a negative effect on the fertility of gilts. Also the studies by Klocek [1998], Koczanowski et al. [2000] and Walkiewicz et al. [1994] show that gilts reach high live weight gain fast, as a result of which they are used for breeding earlier and their high level of lean content of body results in a decrease in energy reserves found in the organism in the form of fat. Along with an increase in lean content of body the backfat thickness decreases. In the course of the analysed years it was shown that in 2002 the lowest backfat thickness (9.76 mm) was accompanied by the highest content of lean meat 58.1%. In the opinion of Rozeboom et al. [1996] reaching by a gilt at a given age minimum threshold levels of body weight and fatness are a necessary, though not the only, precondition of the future high reproductive performance. Walkiewicz et al. [1994] reported that gilts with a thinner backfat layer had less numerous litters, showed poorer maternal care for their progeny, and exhibited symptoms of the next oestrus later. Milk of these sows contained also less fat and unsaturated fatty acids. In the investigated population a mean of 3.13 litters were obtained from a sow (Tab. 2) the herd size affecting the trait considerably. Sows from herds of animals (group II) during their productive live delivered on average more litters (3.95) than those from small (group I; P 0.01) or large herds (group III; P 0.01). Also the mean number of piglets /litter of sows in group II was the highest: piglets at birth and on day 21. Piglet mortality up to day 21 was low, with a mean of 0.56 (4.49%). It was lowest in sows from group III of herds (P 0.01 in relation to group I and II ). The mean age at first farrowing was 356 days, being by 4 days lower from the 2003 national mean and showing no relation to herd size. The age of sows at first farrowing had a significant effect on the fertility and lifetime productivity of sows, measured by the number of litters obtained in the whole reproductive period. According to Szostak 106

5 Genetic and Breeding Research on Pigs with Special Reference to Indigenous Breeds Table 2. Reproductive performance traits of sows in herds of different size Trait 19 sows Herd size sows 50 sows Herds pooled mean 2.73 B 3.95 A 2.77 B 3.13 Number of litters from SD one sow min max Number of piglets born in litter Number of piglets on day 21 mean A A B SD min max mean Bb Aa ab SD min max Piglet mortality (head) mean 0.65 B 0.58 B 0.47 A 0.56 SD Piglet mortality (%) mean 5.35 BD 4.56 BC 3.69 A 4.49 SD Age at first mean farrowing (days) SD Farrowing interval mean 183 B 184 B 175 A 180 (days) SD Age of sow mean 797 B 1015 A 832 B 883 at culling (days) SD Productive life (days) mean 442 B 656 A 479 B 527 SD aa... Within rows means bearing different superscrips differ significantly at: small letters P 0.05; capitals P [2001], at a too early mating of gilts the pregnancy and later lactation are exhausting for the organism of the sow. However, a delayed first service, apart from increasing maintenance costs, may also lead to problems with fertilization. Similarly, Milewska and Grudniewska [1985] stated that designating sows for reproduction as late as at the age of 9 months resulted in rearing one litter less compared to sows serviced earlier. The former were also culled earlier. Also Le Cozler et al. [1997] observed poorer reproduction performance in older gilts. 107

6 W. Milewska Herd size had a significant effect on the age of sows at culling. In herds from group II with an moderate number of sows the animals were culled the latest on day 1015 (P 0.01 in relation to group I and III). In the other two herd size groups the age at culling was similar and amounted to 797 days in group I, and 832 days in group III (P 0.01). Tested sows were used on average for 527 days. The length of their productive live is a trait which should be taken into account at the selection of sows for further breeding. As it was reported by Lewczuk et al. [11], the best results are obtained from sows rearing up to 6 litters; subsequently reproductive performance deteriorates leading to the shortening of the productive life of sows to about 3 years. In this study analysed sows were used for a shorter period, which in combination with the mean number of their litters (3.13) shows their intensive use. The mean farrowing interval was 180 days (Tab. 2). It was the shortest in group III (175 days), and differed highly significantly from the interval found in other groups. The recommended optimum farrowing interval is days, which makes it possible to obtain 2 to 2.2 litters/sow yearly. Fertility of multiparous sows was higher than in primiparous sows, amounting to and piglets at birth and and 10.8 piglets on day 21, respectively (Fig. 1). Performance of primiparous sows was similar to the national mean, which in 2002 was piglets at birth and on day 21 [Milewska i Grudniewska 1985], whereas litter size of multiparous sows was higher (Fig. 1). Litter size was significantly affected by the breed of dams and sires. No advantageous effect of crossing was found on litter size. Purebred PLW litters were larger than crossbred PLW PL litters, both at birth and on day 21 (Fig. 1). The highest number of purebred piglets at birth was Fig. 1. Litter size. 108

7 Genetic and Breeding Research on Pigs with Special Reference to Indigenous Breeds Fig. 2. Mean number of purebred piglets at birth and on day 21 depending upon litter parity. Fig. 3. Mean number of crossbred piglets at birth and on day 21 depending upon litter parity. found in the 3rd litter piglets (Fig. 2). In case of two-breed litters the fertility of sows varied (Fig. 3) which shows that heterosis is a one-time phenomenon and it is difficult to predict its effect. Moreover, a significant role is played by the position of a given breed in crossing, both on the maternal and paternal side [Czarnecki et al. 2000]. In a study by Milewska and Falkowski [2004] larger litters were obtained of PL sows serviced by PLW boars than in the opposite breed combination. 109

8 W. Milewska On the basis of the results presented the following conclusions may be drawn. In the PLW population in the years of the Warmia and Mazury region the share of small herds in which no more than 20 sows were kept, was too high. Means for individual performance traits of sows were similar to the national means for the PLW breed in Also the fertility of primiparous sows in the period analysed was high and close to the national mean, whereas fertility of multiparous sows was higher than the national mean. Sows kept in medium-sized herds (20-49 sows) had the longest productive lives, and gave the highest number of litters and the highest number of piglets per litter. They also had the best results in raising piglets. Purebred PLW litters were bigger in size than two-breed litters (PLW PL), which means that mating PLW sows to PL boars did not bring about the expected advantageous heterosis effect in this respect REFERENCES BUCZYŃSKI J., 1988 Kształtowanie się niektórych cech reprodukcyjnych u czterech pokoleń świń rasy pbz, hodowanych w stadzie zamkniętym (Selected reproduction traits in four generations of Polish Landrace pigs kept in a closed herd). Thesis. In Polish. Roczniki Akademii Rolniczej w Poznaniu, Rozprawy Naukowe 184. CZARNECKI R., OWSIANNY J., JACYNO E., PIETRUSZKA A., DELIKATOR B., 2000 Użytkowość rozpłodowa loch mieszańcowych (wbp pbz) krytych knurami pochodzącymi z reciprokalnego krzyżowania ras pietrain i duroc (Breeding performance of cross-bred sows (Polish Large White Polish Landrace) serviced by boars coming from reciprocal crossing of Pietrain and Duroc breeds In Polish. Biuletyn Naukowy 7, DUNIEC H., 1984 Metody zmierzające do podniesienia użytkowości rozpłodowej, tucznej i rzeźnej świń (Methods to improve breeding, fattening and slaughter performance in pigs). In Polish. Trzoda Chlewna, 22 (5): 3-7. ELIASSON L., RYDHMER L., EINARSSON S., ANDERSSON K., 1991 Relationship between puberty and production traits in the gilt. 1. Age at puberty. Animal Reproduction Science 15, JOHANSSON K., KENNEDY B., 1983 Genetic and phenotypic relationships of performance test measurement with fertility in Swedish Landrace and Yorkshire sows. Acta Agriculturae Scandinavica 33, KLOCEK C., 1998 Skracanie okresu odpoczynku poprawia rezultaty użytkowości rozpłodowej loch (Shortening of rest period improves breeding performance of sows). In Polish. Trzoda Chlewna 31(1), 14. KOCZANOWSKI J., MIGDAŁ W., KLOCEK C., STAWARZ M., 2000 Wpływ otłuszczenia przed pokryciem loch na ich dalszą użytkowość rozpłodową (The effect of fatness before servicing of sows on their future breeding performance). In Polish. Biuletyn Naukowy 7, KULISIEWICZ J., 1988 Znaczenie cech użytkowości rozpłodowej w selekcji świń w wybranych stadach zarodowych rasy wbp (The importance of breeding performance traits in selection of pigs in selected breeding herds of Polish Large White breed). In Polish. Zeszyty Problemowe Postępów Nauk Rolniczych Zootechnika. 335, LECHOWSKA J., KUSZ D., 2003 Wartość rozpłodowa loch zarodowych polskiej białej zwisłouchej wpisanych do rejestru użytkowości rozpłodowej (Breeding value of pedigree Polish Landrace sows entered in the breeding performance register). In Polish. Przegląd Hodowlany. 4,

9 Genetic and Breeding Research on Pigs with Special Reference to Indigenous Breeds LE COZLER Y., DAGORN J., LINDBERG J.E., AUMAITRE A., DOURMAND J.Y., 1997 Effects of age at first farrowing on long term productivity of sows. Proceedings of the 48th Annual Meeting of the EAAP, Vienna. LEWCZUK A., GRUDNIEWSKA B., JANISZEWSKA M., 1991 Zmiany w użytkowości rozpłodowej loch rasy wielkiej białej polskiej w latach na terenie OSHZ w Olsztynie (Changes in breeding performance of Polish Large White sows in the years in the area of OSHZ in Olsztyn). In Polish. Zeszyty Naukowe Przeglądu Hodowlanego 1, MILEWSKA W., GRUDNIEWSKA B., 1985 Produkcyjność loch rasy wbp w indywidualnych gospodarstwach hodowlanych okręgu olsztyńskiego w zależności od wieku przy pierwszym pokryciu (Productivity of Polish Large White sows in privately-owned breeding farms in the Olsztyn district in terms of age at first mating). Proceedings of the International Conference Prospects for animal breeding in Poland. Wrocław, vol. I., MILEWSKA W., FALKOWSKI J., 2004 An attempt to evaluate litters produced by reciprocal crossing of Polish Large White and Polish Landrace pigs. Annals of Animal Science Supplement 2, ORZECHOWSKA B., MUCHA A., 2003 Wyniki użytkowości rozpłodowej loch ras matecznych w roku 2002 (Breeding performance of sows of maternal breeds in 2002). In Polish. Trzoda Chlewna. 7, ROZEBOOM D.W., PETIGREW J.E., MOSER R.L., CORNELIUS S.G., KANDEGLY S.M., 1996 Influence of gilt age and body weight at first mating on sow reproductive performance and longevity. Journal of Animal Science 74, STASIAK A., KAMYK P., DZIURA J., 2002 Ocena różnicy selekcyjnej w cechach reprodukcyjnych loch zarodowych rasy pbz utrzymywanych na Lubelszczyźnie (Assessment of selection differential in breeding performance traits of pedigree Polish Landrace sows in the Lubelszczyzna region). In Polish, summary in English. Annales Universitatis Mariae Curie-Sklodowska XXI, 39, SZOSTAK B., Zmiany długości okresu międzymiotu loch hodowlanych w rejonie lubelskim (Changes in farrowing interval length in pedigree sows in the Lublin region). In Polish. Przegląd Hodowlany 7, TYRA M., RÓŻYCKI M., 2000 Odziedziczalność cech rozpłodowych różnych ras świń (Heritability of breeding traits in sows of different breeds). In Polish, summary in English. Zeszyty Naukowe Przeglądu Hodowlanego 48, WALKIEWICZ A., WIELBO E., KAMYK P., STASIAK A., 1994 Analiza zmian masy ciała i grubości słoniny u loch żywionych wg norm (Analysis of changes in body weight and backfat thickness in sows fed according to standards). Scientific Conference Modern pig feeding standards. In Polish, summary in English. Jabłonna, Wanda Milewska Cechy użytkowe loch rasy wbp utrzymywanych w stadach hodowlanych Warmii i Mazur w latach S t r e s z c z e n i e Opracowaniem objęto 1337 loch pochodzących z 70 stad i 4173 uzyskane od nich mioty: 1900 czystorasowych miotów wbp wbp i 2273 mioty mieszańcowe wbp pbz. Lochy były użytkowane 111

10 W. Milewska w stadach hodowlanych Warmii i Mazur w latach i kojarzone z knurami wbp lub pbz. Charakterystyki użytkowości rozpłodowej loch dokonano dzieląc je na trzy grupy, zależnie od wielkości stad, w których je utrzymywano: do 19 loch w stadzie, od 20 do 49 loch w stadzie i 50 lub wiecej loch w stadzie (odpowiednio grupa I, II i III). W badanej populacji uzyskano od jednej lochy średnio 3,13 miotów. Na wartość tej cechy w znacznym stopniu wpływała wielkość stada. Lochy utrzymywane w stadach zaliczonych do grupy II były użytkowane najdłużej i w związku z tym urodziły średnio w całym okresie użytkowania istotnie (P 0,01) więcej miotów (3, 95) niż lochy w stadach grupy I i III (odpowiednio 2,73 i 2,77). Również średnia liczba prosiąt w miotach loch grupy II była najwyższa i wynosiła 11,93 przy urodzeniu i 11,34 w dniu 21. Śmiertelność prosiąt do 21 dnia życia była niska i wyniosła średnio 0,56 prosięcia (4,49%). Była ona najniższa w III grupie stad, a różnice w stosunku do pozostałych dwóch grup były wysokoistotne (P 0,01). 112