Effect of replacing fish meal by a mixture of  ensiled taro (Colocasia esculenta) foliage and  sweet potato vines (Ipomoea batatas L.) on reproduction and piglet performance in VanPa  sows in  central Vietnam 

Tran Thanh Hai, Nguyen Thi Hoa Ly and T R Preston* 

Hue University of Agriculture and Forestry, Vietnam
Thanhhai1406@gmail.com
*UTA, TOSOLY, AA48 Socorro, Santander, Colombia

Abstract

Eighteen Van pa sows (3rd -5 parity and live weight about 50 -60 kg) was selected to carry out the on station, allocated randomly into three groups, with each group consisting of 6 pigs. The pigs were kept individually in concrete floor pens. All Van Pa sows in each group were mated by with the semen of the same purebred Van Pa boar. The trial was designed as complete randomized block with 3 treatments and 6 replicates in which the protein source was supplied from a mixture of  50 % ensiled taro foliage  (ETS) and 50 % ensiled sweet potato vines (ESPV) in DM  and fish meal. Treatment FM (control diet): Basal diet contains rice bran, cassava root meal, fish meal. Treatment T50: Basal diet with 50 % of protein from fish meal replaced by protein from a mixture of ensiled  taro foliage and sweet potato vines. Treatment T100: Basal diet with 100 % of protein from fish meal replaced by protein from a mixture of ensiled taro foliage and sweet potato vines. The feed allowance was fixed at 2.5 % of body weight in pregnancy and ad libitum in lactation. Protein levels was 12 % in DM in the diets for pregnancy and 13 % for lactation.

The results showed that there were no significant differences in DM, CP intake among treatments for two period pregnancy and lactation period of Van Pa sows (P>0.05). However, total CF intake significant increased with increased amount of a mixture of  ensiled taro foliage and sweet potato vines  in diet of Vanpa sows (P<0.001). The results also showed that no significant dietary treatment effects were found for any of piglet performance at birth. The total mean number of piglets born per litter was 6.33, 7.33 and 6.5 in treatments FM, T50 and T100, respectively (P>0.05).  Similar, there were no significant differences in total litter size, total litter weight and percentage mortality among treatments at weaning. The total mean number of piglets per litter at weaning was 5.50, 5.83 and 5.83 in FM, T50 and T100, respectively (P>0.05). There were significant differences in mean piglet live weight at 21 days and at weaning, the mean piglet live weight were decreased with increased amount of a mixture of  ensiled taro foliage and sweet potato vines  in diet of Vanpa sows (P<0.001). No significant dietary treatment effects were found for any of the reproductive traits of Van pa sows.

It is concluded that a mixture of ensiled taro foliage and sweet potato vines  in diet of Vanpa sows in pregnancy and lactation without affecting reproduction criteria, measured as numbers of live piglets born and weaned, and the interval from weaning to estrus. Using protein from a mixture of ensiled  taro foliage and sweet potato vines in diet of Vanpa sows reduced feed cost/kg piglet by 5- 8.4 %.

Key words: Van pa sow, piglet performance, reproduction, ensiled taro foliage, ensiled sweet potato vines. 

Introduction 

Van pa is an indigenous pig breed that is well adapted to the environmental conditions of smallholder in the uplands in Quang Tri province in Central Vietnam. This pig breed has been kept mainly under scavenging system, and they are raised by the ethnic minorities Van Kieu and PaKo people in Quang Tri province due to their advantages, for example high environmental adaptability, good disease resistance, and the ability to utilise poor nutritional quality food.  Van Pa sows have  low reproduction and growth performance (Hoa Ly et al., 2010a), and piglet body weight at birth is only  0.29 kg/piglet, litter size of only 4.53 piglets/litter, body weight at 120 days old of only 10.38kg/pig (Tran Thanh Hai and Le Dinh Phung, 2009). The smallholder rearing conditions include feeding fibre-rich diets with low energy and protein. So it is very important to help farmers in this area improve the performance of this breed of pig. Conventional feeds are the main protein supplements in the region, including concentrate feed, groundnut cake and fish meal, but they are relatively expensive and are not available in the mountainous villages.

Sweet potato is known as a potentially valuable feed crop with a high adaptability to different climatic and soil conditions. It has a high yield of both tuber and vines (Woolfe 1992; An et al 2003; Hoa Ly et al., 2010b). In many areas, sweet potato leaves are consumed and varieties are grown which are suitable for harvesting of both tubers and leaves, or for harvesting leaves only. Sweet potato is not only used for human consumption but also for animal feed, because of its nutritional properties. In sweet potato vines the CP content in DM can range from 16 to 29% (Farrell et al., 2000; Hartemink et al., 2000; Dung, 2001, An et al., 2003). Sweet potato contents of minerals and vitamins such as A, B2, C and E are rather high in leaves in comparison with other vegetables. For this reason, both leaves and vines are used as a protein and vitamin source for pigs  (Monra et al., 1992, Hoa Ly et al., 2010b;  Hoa Ly et al., 2012).

Taro (Colocasia esculenta (L.) Schott) can be a potential protein source for animals, especially pigs due to the good nutritional quality of the leaves. Many studies have been done on using taro for pigs (Chittavong et al., 2006, 2008; Tiep et al., 2006; Pheng Buntha et al, 2008; Rodriguez et al, 2009, Duyet, 2010). Chittavong et al (2008) reported that a mixture of taro silage and water spinach can  replace 100% of soybean meal in pregnancy and lactation diets for Mong cai gilts without affecting sow reproduction. Sivilai et al (2010) concluded that a mixture of taro leaf silage and water spinach can be used in the diet of Mong Cai gilts in pregnancy and lactation without affecting reproduction criteria, measured as numbers of live piglets born and weaned, and the interval from weaning to estrus. The sows can obtain these nutrients by feeding them a high forage diet. Le Thi Men, et al (2000) and Hoang Nghia Duyet, et al (2003, 2004) showed that a suitable proportion of forage leaves in the diet of Mong Cai sows is 30 - 40 % (in DM) in the pregnancy period and 20 - 30% in the lactation period.

There are difficulties in using taro as animal feed because of its content of oxalic acid and other anti-nutritional factors that cause the mouth and throat of animals consuming it to itch. However, ensiling can be the most appropriate method to preserve taro and cassava leaves and reduce anti-nutritional factors in taro and cassava leaves for feeding pigs (Tiep et al, 2006; Hang and Preston, 2010).

In the uplands of Central Vietnam cassava and vegetables (such as taro, sweet potato vines) based pig production systems are very common and play an important role in the economics of small farms. However, up to now no data can be found on on reproduction and piglet performance in VanPa sows. Further research is needed to help farmers in this area on how to use the local protein source from taro or sweet potato vines as the major protein supplement for Van Pa sows with the aim to improve their reproduction and piglet performance. 

 This study therefore aims to determine the effect of replacing fish meal by a mixture of ensiled taro foliage and sweet potato vines in diets on reproduction and piglet performance in VanPa sows in Quang Tri province.

Materials and methods

Ensiling

Sweet potato vines were harvested at 60 days after planting, with subsequent harvests at 20-day intervals. At time of harvest, 50 % of the total branches was cut at 10 cm distance from the main stems. The vines were chopped into small pieces of 2- 3 cm and spread out on the floor overnight for wilting to reduce the moisture content. The wilted sweet potato vines was mixed with 0.5 % Nacl of the wilted weight of the vines.  

The fresh foliage taro were collected 4 - 6 months after planting with subsequent harvests at 15- 20 day intervals and spread out on the floor 15 hours for wilting, chopped into small pieces (2 - 3 cm), mixed with 0.5 % salt of wilted taro foliage. The silages of sweet potato vines or taro foliage was kept in sealed airtight plastic bags with a capacity of 30 kg and was stored for 14 days prior to feeding.

Samples of silage was taken after 14 days after ensiling and was evaluated by approximate analysis for, DM, CP, CF, OM (AOAC 1990).  The analysis was done in the Hue University laboratories from January 2011 to March 2011. 

Treatments, animals and experimental design

The experiment was carried out  on station  at the research farm of Quang tri province from January to September  2011. Eighteen Van pa sows (3rd -5 parity and live weight about 50 -60 kg) was selected to carry out the on station, allocated randomly into three groups, with each group consisting of 6 pigs. All Van Pa sows were allocated randomly into three treatments with 3 different levels of a mixture of ensiled taro foliage and sweet potato vines. The pigs were kept individually in concrete floor pens.

All Van Pa sows in each group were mated by with the semen of the same purebred Van Pa boar. Three weeks after mating, the sows were fed the experimental diets. The trial was designed as complete randomized block with 3 treatments and 6 replicates in which the protein source was supplied from a mixture of 50 % ensiled taro foliage (ETS) and 50 % ensiled sweet potato vines (ESPV) in DM  and fish meal (Table 3).  

Three treatments were:

• Treatment FM (control diet): Basal diet contains rice bran, cassava root meal, fish meal
• Treatment T50: Basal diet with 50 % of protein from fish meal replaced by  protein from a mixture of ensiled  taro foliage and sweet potato vines.
• Treatment T100: Basal diet with 100 % of protein from fish meal replaced by protein from a mixture of ensiled  taro foliage and sweet potato vines.

Diets and feeding

The diets contained rice bran, cassava root meal, and fish meal and a mixture of  ensiled taro foliage and sweet potato vines.  The feed allowance was fixed at 2.5 % of body weight in pregnancy and ad libitum in lactation. Protein levels was 12 % in DM in the diets for pregnancy and 13 % for lactation (Table 3 ). The pigs was given three equal meals per day (07:00, 11:00 and 17:00 h), the refused feed was collected and recorded daily.  Water was available ad-libitum.  Feed chemical composition was analyzed at the laboratory of the University before the start of the experiments.  The composition of the feed ingredients of the control and experimental diets is shown in the table 2.

Measurements

- Feed intake (recording feed intake in pregnancy and lactation stage)

- Stillbirths and mortality of the piglets after birth and during lactation stage (%)

- Litter size at birth and at weaning (piglets/ litter).

- Live weight of the piglets at birth and at weaning (kg/ piglet).

- Litter weight of piglets at 21 days of age

- FCR and price for producing 1 kg of wean piglet (kg feed/ kg wean piglet and price).

- Benefit between treatments

Chemical analysis

The chemical composition of feed was determined according to standard methods (AOAC, 1990). Dry matter (DM) was measured by drying fresh samples at 100^oC for 24 hours. Total nitrogen (N) was determined by the Kjeldahl method and crude protein (CP) was calculated from total nitrogen (N*6.25). Ether extract (EE) was determined by Soxhlet extraction without prior acid hydrolysis. Ash was the residue after ashing the samples at 550 to 600⁰C.  

Statistical analysis

Data from the experiment was analyzed by ANOVA using the General Linear Model (GLM) procedure (Minitab Version 14, 2004). Pair-wise comparisons with a confidence level of 95 was used to determine the effects of dietary treatment between groups. Results was presented as Least Squares Means with their pooled standard errors.

Results and discussion

Feed  intake

Effect of replacing fish meal by a mixture of ensiled taro foliage and sweet potato vines  on daily feed and nutrient intakes of Van Pa sows during pregnancy and lactation is shown in table 4. There were no significant differences in DM, CP intake among treatments for two period pregnancy and lactation period of Van Pa sows (P>0.05). However, total CF intake significant increased with increased amount of a mixture of  ensiled taro foliage and sweet potato vines  in diet of Vanpa sows (P<0.001, Table 4).

Piglet performance in lactation

Litter size and piglet live weights at birth, 21 days and weaning are shown in Table 5.

The data in table 5 show that no significant dietary treatment effects were found for any  of piglet performance at birth. The total mean number of piglets born per litter was 6.33, 7.33 and 6.5 in treatments FM, T50 and T100, respectively (P>0.05). The number of piglets born alive and live weight were not different (P>0.05) among treatments. Percentage mortality at birth was numerically higher on the T50 diet but the differences were not significant (P= 0.703). The total number of piglets, live weight and percentage mortality at 21 days were not different among treatments (P>0.05). Similar, there were no significant differences in total litter size, total litter weight and percentage mortality among treatments at weaning. The total mean number of piglets per litter at weaning was 5.50, 5.83 and 5.83 in FM, T50 and T100, respectively (P>0.05). There were significant differences in mean piglet live weight at 21 days and at weaning, the mean piglet live weight were decreased with increased amount of a mixture of  ensiled taro foliage and sweet potato vines  in diet of Vanpa sows (P<0.001, Table 5).

Reproductive traits

No significant dietary treatment effects were found for any of the reproductive traits of Van pa sows. The days weaning to estrus around 15 days and the litters/year of Van pa sows around 2.1 (Table 6).  

Effect of replacing fish meal by a mixture of ensiled taro foliage and sweet potato vines on feed conversion ratio (FCR) and feed cost of Van Pa piglets is shown in table 7. There were no significant differences in FCR and feed cost of piglets among treatments (P>0.05). However, the feed cost/kg piglet was reduced with increased amount of a mixture of ensiled taro foliage and sweet potato vines in diet of Van Pa sows. Using protein from a mixture of ensiled taro foliage and sweet potato vines in diet of Van Pa sows reduced feed cost/kg piglet by 5- 8.4 %.

Discussion

Van pa is an indigenous pig breed has ability to utilize poor nutritional quality food and is well adapted to the environmental conditions of smallholder in the uplands in Quang Tri province in Central Vietnam. The use of a high level of inclusion of a mixture of ensiled taro foliage and sweet potato vines in the diet of Van Pa sows but there were no significant differences in DM, CP intake among treatments for two periods pregnancy and lactation of Van Pa sows. This was demonstrated that Van Pa sows is likely to take advantage of raw green feed. However, total CF intake significant increased  with increased amount of a mixture of  ensiled taro foliage and sweet potato vines  in diet of Vanpa sows due to high CF content in ensiled taro foliage (148 g/kg DM) and in sweet potato vines (155 g/kg DM).

This finding is in agreement with Duyet et al. (2006) who reported that litter size of Mong Cai sows was not affected when the soybean meal was replaced by a mixture of fresh leaves (from cassava, water spinach and sweet potato) in diet. However, piglet performance of Van Pa sows is lower than in compared with Mong cai sows due to this breed Van Pa sows have  low reproduction and growth performance. Recently, Tran Thanh Hai and Le Dinh Phung (2009) reported that Van Pa sows have low reproduction and growth performance, piglet body weight at birth is only 0.29 kg/piglet, litter size of o 4.53 piglets/litter, body weight at 120 days old of only 10.38kg/pig. This breed has a too low growth rate of about 3-4 kg/ month (Hoa Ly et al, 2010a). In this study, the piglet performance of Van Pa were higher than these data showed in reported by these authors because in diets of this study has higher in CP (12 % - 13 %) compared diets  of Van Pa sows (8-10 % CP).  However, the  mean piglet live weight at 21 days and at weaning were decreased may be the higher CF content with increased amount of a mixture of  ensiled taro foliage and sweet potato vines  in diet of Vanpa sows.

The length of pregnancy in this experiment is similar to the results of Loc et al (2000), who also reported that the length of pregnancy was not different among treatments when increasing levels of ensiled forages were included in the diets of Mong Cai sows. The results from this experiment contrast with those of Nga et al (2000) who reported that Mong Cai sows returned to estrus within 15.8 days after weaning at 49 days, when fed 10.3 % of CP from cassava leaf meal and water spinach during pregnancy.

Conclusions

• A mixture of ensiled taro foliage and sweet potato vines can replace 100 % of fish meal in pregnancy and lactation diets for Van Pa sows without affecting sow reproduction, measured as numbers of live piglets born and weaned, and the interval from weaning to estrus.
• However, weights of piglets at weaning decreased with a linear trend as the fish meal was replaced by the mixture of ensiled taro foliage and sweet potato vines.
• Using protein from a mixture of ensiled taro foliage and sweet potato vines in diet of Van Pa sows reduced feed cost/kg Van Pa piglet by 5- 8.4 %.

Acknowledgements

We are very grateful to the Swedish International Development Cooperation Agency, Department for Research Cooperation (Sida-SAREC) through the regional MEKARN Project, for the financial support of this study.

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