Studies on some production and carcass traits of Mong cai and their crosses in North Vietnam.

Abstract

Proc. Assoc. Advmt. Anim. Breed. Genet. Vol12 STUDIES ON SOME PRODUCTION AND CARCASS TRAITS OF MONG CA1 AND THEIR CROSSES IN NORTH VIETNAM N.V. Due ' B.P. Kinghorn * and H.-U. Graser ' i Animal Genetics and Breeding Unit (AGBU)*, UNE, Armidale, NSW, 235 1. * Department of Animal Science, UNE, Armidale, NSW 235 1. SUMMARY A total of 1,879 pure Large White (LW) and Landrace (LR), 481 pure Mong Cai (MC), 194 Fl, 70 backcross and 69 three-breed cross MC pigs from 5 herds in North Vietnam performance recorded between 1984 and 1995 were measured for average daily gain during the test period (TDG), backfat thickness (BF) and feed conversion ratio (FCR). The averages of TDG in LW and LR, MC, Fl, backcross and three-breed cross pig groups were 0.52, 0.28, 0.44, 0.51 and 0.52 kg/day. The estimates of FCR were highest in pure MC (5.18), followed by Fl (4.13), backcross (3.73) and lowest in the three-breed group (3.67). The same trend was apparent for BF in the four groups, MC (36.45) > Fl (27.25) > backcross (23.97) > three-breed cross (23.71 mm) > pure LW and LR (20.95). Heterosis estimates were 10.00, 10.90 and 13.04% for ADG, -4.17, -3.89 and 5.51% for FCR and -5.05, -2.28 and -3.33% for BF in Fl, backcross and three-breed groups, respectively. The three-breed crosses had more desirable TDG, FCR and BF performance than two-breed crosses and much better than purebreds. Pig production and carcass quality in rural areas of North Vietnam, where the conditions for the pig industry are not adequate for developing exotic breeds, may be increased by using three-breed crosses incorporating MC. Keywords: Pigs, crossbreeding, growth rate, feed conversion ratio, backfat thickness INTRODUCTION Pork production is the most important among the Vietnamese animal industries, producing 938,000 tons per year. Pork accounts for about 75% of the total meat production in Vietnam (Cut 1995). During the last 30 years, average of testing period daily gain (TDG, kg/day), feed conversion ratio (FCR, kg feedikg gain), backfat thickness (BF, mm) and various indicators of lean meat percentage (LMP) have been selected for and are considered the most important traits in pig breeding. With increased awareness of the disadvantages of animal fat, the demand for lean meat is ever increasing and pig breeders have been forced to produce pigs with very lean carcasses or low BF. A number of published papers have shown the growth rate of the Mong Cai (MC) breed to be low, at 196 - 300 g/day (Doanh 1994) explaining that pig production in Vietnam, especially using native breeds, is far below the production in other countries. The aim of this paper is to study some production and carcass traits, particularly TDG, FCR and BF of MC and their crosses in north Vietnam. ' Animal Genetics and Breeding Unit (AGBU) 185 Proc. Assoc. Aa'vmt. Anim. Breed. Genet. Vol12 Background information. MC is a popular and important native breed in Vietnam. It is very good in reproductive aspects as well as resistance to stressful environmental conditions. This native pig breed can be well developed in Vietnam, even where the conditions are not good. However, it has a small body size, low TDG, high FCR and high BF. It is widely farmed in mountain areas, where the conditions are not good for rearing exotic purebreds and exotic crosses. During the last 20-30 years, MC has been intensively used for crossing with exotic breeds in order to increase the lean meat percentage, TDG, and reduce FCR. In rural areas, MC and MC crosses have been widely farmed and these animals contribute a significant proportion to the total pig meat production in Vietnam. MATERIALS AND METHODS From 1984 to 1995 a total of 2720 pigs of pure Large White (LW) and Landrace (LR), MC, Fl LW x MC, LR x MC, backcross LR x (LR x MC), LW x (LW x MC) and three-breed crosses LWx (LR x MC), LR x (LW x MC) were recorded for TDG, FCR and BF across 5 herds in north Vietnam. Statistical analysis. Fixed effects considered were herd-year-season (4 breed genotype groups and sex. All these fixed effects were analysed by PROC GLM (SAS 1993) and they were highly significant for each trait also analysed by using a Restricted Maximum Likelihood (REML) univariate animal model (Meyer 1993). RESULTS AND DISCUSSIONS Performance of TDG, FCR and BF for MC and their crosses. for meat production even under poor conditions of pig husbandry environment is not optimal, with food deficiencies and inefficient means for TDG, FCR and BF of MC and MC crosses are presented seasons) of test period, 4 using the SAS procedure (p < 0.01). The data were procedure applied to a MC crosses perform adequately in northern Vietnam, where the management. The least square in Table 1. Table 1. Least square means and their standard errors for TDG, FCR and BF in MC and their crosses Breed MC LW and LR Fl Backcrosses Three-breed crosses TDG 0.28 0.52 0.44 0.51 0.52 (kg/day) f 0.0 1 f 0.01 f 0.01 f 0.01 f 0.01 Trait FCR (k@g) 5.18 f 0.27 3.44 f 0.22 4.13 f 0.28 3.73 f 0.3 1 3.67 f 0.32 BF 36.45 20.95 27.25 23.97 23.71 (mm) f 0.25 f 0.18 f 0.20 f 0.26 f 0.47 TDG increases from pure MC to Fl, backcross and is highest in three-breed cross pigs. This value (0.52 kg/day) was higher than the estimated value of 0.36 (Vong et al. (1986). However, this value was slightly lower than the value of 0.55 kg/day for Fl (Landrace x MC) in the National Institute 186 Proc. Assoc. Advmt. Anim. Breed Genet. VoI 12 of Animal Husbandry herd, where Landrace (LR) came from Belgium (Tuyen 1989). In threebreed groups, TDG was higher than that of 0.49 kg/day at the Binh Thang centre (Hai et al. 1990). Estimates of FCR decrease from pure MC pigs to Fl, back and three-breed cross pigs. These fmdings were lower than the estimates of 4.89 kg/kg (Harm et al. 1991) and 4.4 kg/kg (Hai and Vien 1991). In contrast, our FCR estimate in the Fl group was higher than the values of 3.96 and 4.00 kg/kg (Tuyen 1989), from different Fl (LR x MC) herds, where LR came from Belgium and Japan, and 4.05 kg/kg found by (Vong et al. 1986) in another FI genotype herd. BF followed the Fl group, The value of value for BF the same pattern as FCR, reducing from 36.45 mm in pure Mong Cai to 27.25 mm in to 22.97 mm in the backcross, and even lower in the three-breed groups (23.7 1 mm). BF of MC in our study was close to the finding of 36.70 (Nhon and Hot 1977). The in F 1 was lower than those reported by Hanh et al. (199 1). Heterosis in Mong Cai crosses. Most production and carcass traits can be improved by selection because their heritability is moderate to high. They may be further improved in crossbred animals due to the effects of heterosis. The benefit of heterosis is to produce pigs more efficiently for slaughter and this has been used effectively by numerous commercial producers for many years in Hanoi and HoChiMinh City, but not in the countryside areas of Vietnam. Crossbreeding between exotic and native breeds has been carried out for the last 30 years in some places in Vietnam in order to exploit heterosis (Thien et al. 1984). Nowadays, MC crossbred pigs are used in nearly all commercial herds in north Vietnam. Heterosis estimates for TDG, FCR and BF of Mong Cai crosses are presented in Table 2. Heterosis for TDG in Fl and backcross groups was similar, but it was higher for the three-breed cross groups. This finding is lower than the estimates of 11.5% in crossbred progeny of Hampshire and LR (Baas et al. 1992), but higher than that of 5.48% in three-breed crosses between improved Chinese pigs and exotic breed sires (Jin and Mao 1994). Heterosis for FCR of these three genotype groups ranged from -3.89 to -5.51%. This estimate was higher than the estimate of -2.5% in the crossbred dam Hampshire x LR (Baas et al. 1992). However, this was lower than the value of 9% which was found for two-breed crosses between improved Chinese pigs and exotic breeds (Jin and Mao 1994). In general, the hybrid animals have more desirable FCR than the purebreds. Our BF heterosis estimates are higher than the estimate of -0.9% in the crossbred dam Hampshire x LR (Baas et al. 1992). This table illustrates the hybrids had lower BF than their purebred counterparts. However, heterosis for carcass traits, for example BF was expected to be low (Serres 1992). In conclusion, three-breed crosses, which are 25% MC, had better TDG, FCR and BF than Fl of MC and much better than pure MC. To increase pig production and carcass performance in rural areas of Northern Vietnam, where conditions for rearing exotic breeds are not adequate, the variation of temperatures is high together with high relative humidity, food quality is low and management is inefficient, three-breed crosses of MC, such as LR x (LW x MC) or LW x (LR x 187 Proc. Assoc. Advmt. Anim. Breed. Genet, Voll2 MC) may be used. More detailed modelling studies are required to identify which crosses are most economically and logistically appropriate for each region. Table 2. Heterosis (Oh) of TDG, FCR and BF of MC crosses Breeds MC LW and LR Fl Backcrosses Three-breed crosses TDG N Mean Heterosis 481 0.28 0.00 1,879 0.52 0.00 194 0.44 10.00 70 0.51 10.90 69 0.52 13.04 FCR N Mean Heterosis 481 5.18 0.00 1,362 3.44 0.00 194 4.13 -4.17 70 3.73 -3.89 69 3.67 -5.51 BF N Mean Heterosis 426 36.45 0.00 1,879 20.95 0.00 194 27.25 -5.05 70 23.97 -2.28 69 23.71 -3.33 However, small herd size and low challenge. It seems that government development of parental seedstock, advisory service. This would help to pig production exploiting the benefits paper. infrastructure in rural areas will make implementation a and other agencies could play a most useful role in the distribution of these parent animals, and provision of an educate farmers and develop cooperatives for more efficient of crossbreeding, some of which have been identified in this REFERENCES Baas, T.J., Christian, L.L. and Rothschild, M.F. (1992) J. Anim. Sci., 70:99. Cut, N.S. (1995) Nong nghiep Vietnam (1945-95) [Agriculture of Vietnam]. NXB Thongke. Hanoi. Doanh, P.H. (1994) KQNCBTQGVN, Tr: 97. Hai, L.T. and Vien, N.T. (1991) KHKTNN. Bo Nong Nghiep and CNTP, 3: 127. Hai, L.T., Thong, T.T., Hien, N.T., Thao, N.H., Vien, N.T., Phuoc, T.H. and Tinh, T.V. (1990) KQNCKH_( 1986- 1990). Vien KHKTNNMN. Chuong Trinh 02B, Tr: 200. Hanh, T.Q., Han, T.Q. and Hue, P.H. (1991) KI-IKTNN. Bo Nong Nghiep and CNTP, 10:467. Jin, R. B. and Mao, J. D. (1994) Pig News and Info., 15:67. Meyer, K. (1993) DFREML. Version 2.1. User notes. Nhon, T. and Hot, V.T. (1977) KHKTNN.Bo Nong Nghiep and CNTP, 5:282. SAS/STAT. (1993). User's Guide Vol. 2, fourth edition, SAS Institute Inc., Cary, NC. Serres, H. (1992) Manual of pig production in the tropics. published by C. A. B. International. U.K. Thien, N., Doanh, P.H. and Luan, D.H. (1984) TTCTNC Chan Nuoi (1969-1984). NXBNN, Tr: 41. Tuyen, C.Q. (1989) TTKHKT Chan Nuoi. Vien Chan Nuoi, 1:11. Vong, C.X., Cat, T.T. and Khai, T.T. (1986) KHKTNN. Bo Nong Nghiep and CNTP, 5:223. 188