Effect of replacing soybean meal by a mixture of taro leaf silage and water spinach on reproduction and piglet performance in Mong Cai gilts
 

Malavanh Chittavong, T R Preston^*and Brian Ogle^**

Faculty of Agriculture, National University of Laos (NUOL), Vientiane city,Lao PDR
malavanc@yahoo.com
^* UTA, TOSOLY, AA #48, Socorro, Santander, Colombia
^** SwedishUniversity of Agricultural Sciences, Department of Animal Nutrition and Management, PO Box 7024, 750 07, Uppsala, Sweden

Abstract

Fifteen Mong Cai gilts weighing 46±3.9 kg at service were used in a Randomized Complete Block Design (RCBD), with five replications of three treatments: TW0, 100% of supplementary protein supplied by soybean meal; TW50, 50% of supplementary protein supplied by soy bean meal and 50% by a mixture of ensiled taro leaves and water spinach, and TW100, 100% of supplementary protein supplied by a mixture of ensiled taro leaves and water spinach. In the pregnancy period the feed was restricted to 1.5% of live weight. In the lactation period the gilts were fed increasing amounts of the same diet up to five days after farrowing, and from then onwards feeds were offered ad libitum.

Total dry matter (DM) intake decreased slightly with increased amounts of the mixture of taro leaf silage and water spinach. Live weights at farrowing and weaning declined as the amount of the mixture of taro leaf silage and water spinach increased. The feed conversion ratios (FCR) for treatments TW0, TW50 and TW100 were 3.09, 3.96 and 5.02 kg feed/kg gain, respectively. Live weight loss and percentage live weight loss in lactation were not affected by diet. The number of piglets born alive and at weaning did not differ among treatments (P>0.05). However, live weights of the litter at birth and weaning and weights of individual piglets declined as the foliages replaced soybean meal. Mortality to weaning ranged from 10.2 (TW0) to 7.5% (TW50) and was not affected by the treatments.

It is concluded that reproduction in the Mong Cai breed, measured as numbers of piglets born alive and weaned, and the interval from weaning to estrus was satisfactory when taro leaf silage and water spinach replaced soybean meal. However, weights of piglets at weaning decreased, with a linear trend from 35.9 to 25.1 kg as the soybean was replaced by the forages.

Key words: Mong Cai gilts, piglet performance, reproduction, taro leaf silage, water spinach

Introduction

Pigs are widely kept throughout the country of Laos, with 64 percent of all households involved in pig production (Kaufmann et al 2003). The number of pigs kept by smallholders varies between an average of 1.4 and 3.7 animals per household, depending on the region (Kaufmann et al 2003). Pigs are normally raised in a free-range system, and supplemented by rice bran and other household waste products (http://clubs.uow.edu.au/clubs_websites/oxfam/Why%20Pigs.pdf). There are some large-scale pig enterprises close to Vientiane, but these use purchased concentrate feeds, which are not a viable option for small-scale farmers in the remote upland areas.

In view of the increasing costs of concentrate feeds, and especially protein concentrates such as soybean and fish meal, recent research in Vietnam, Cambodia and Laos has been directed to the use of leaves from crops such as cassava (Hang and Preston 2005; Chhay et al 2005), sweet potato (An 2004; Malavanh and Preston 2006), and mulberry (Phiny et al 2003), and water plants such as water spinach (Men et al 2000; Ly 2002) and duckweed (Rodriguez and Preston 1996; Hang 1998). Recent research has shown that fresh water spinach was more palatable than cassava leaves for growing pigs, as reflected in higher total DM intake, and the proportion of the diet (47%) provided by the leaves. Digestibility of dry matter, organic matter, N and crude fibre was higher in diets with water spinach than in those with cassava leaves (Chhay and Preston 2005).

Taro leaves (Colocasia esculenta (L.) Schott) are rich in vitamins and minerals. They are a good source of thiamin, riboflavin, iron, phosphorus and zinc, and a very good source of vitamin B6, vitamin C, niacin, potassium, copper and manganese http://en.wikipedia.org/wiki/Taro).Leaves from Taro (Colocasia esculenta (L.) Schott and Alocacia macrorrhiza) and New Cocoyam (Xanthosoma sagittifolium) are traditionally used in pig diets by small-scale farmers in many tropical countries. A preliminary report from Colombia (Rodríguez et al 2006) showed that weight gains in young pigs fed a sugar cane juice diet were the same when the supplementary protein was from a 50:50 mixture of fresh leaves of New Cocoyam and soybean meal compared with soybean meal as the only protein source. Recent research from Vietnam (Duyet et al 2006) showed that there were no differences in live weight loss during lactation and days to first oestrus in Mong Cai sows when all the soybean meal was substituted by a mixture of forage protein sources (water spinach, cassava and sweet potato leaves). In contrast, Large White sows showed a significant deterioration in these traits when all the supplementary protein came from the leaves (Duyet et al 2005).

The present experiment aimed to evaluate the effect of protein-rich leaves as replacement for soybean meal on the performance of Mong Cai gilts during gestation and lactation.
 

Materials and methods

Location and climate

The experiment was carried out from June 2006 to January 2007 at the Faculty of Agriculture, National University of Laos (NUOL), situated about 32 km from Vientiane city, Lao PDR. The mean daily temperature in the area at the time of the experiment was 27 ^oC (range 22-32 ^oC).

Experimental animals and design

Fifteen Mong Cai gilts, with an average live weight at service of 46±3.9 kg, were used in the experiment, and were followed for one complete reproductive cycle. The gilts were imported from Vietnam.

There were three treatments:

• TW0:100% of supplementary protein supplied by soybean meal (no green foliage supplied).

• TW50:50% of supplementary protein supplied by soybean meal and 50% by a mixture of ensiled taro leaves and water spinach (equal parts of each foliage on DM basis).

• TW100:100% of supplementary protein supplied by a mixture of ensiled taro leaves and water spinach (equal parts of each foliage on DM basis).

The experiment was done according to a Randomized Complete Block Design (RCBD) with five replications of each treatment. The gilts were from five litters, with three gilts from the same litter randomly allocated to each treatment. All the gilts were of similar initial body weight.

Housing

The pigs were housed in individual pens made from wood, in an open-sided building with a thatch roof of Imperata grass. The size of each pen was 2.0*1.5m.

Procedure

The energy component of the diet was broken rice and cassava root silage. The composition of the vitamin-mineral premix is shown in Table 1.

Leaves of taro were purchased in Nonveng village, Hatchaifong district, Vientiane City, and made into silage, using molasses (4%, fresh basis). This was found to be the most suitable level of molasses from the results of Chittavong Malavanh et al (2008). The silage was stored for 21 days in plastic bags to ensure complete fermentation. Some of the water spinach was grown in the Faculty farm; but most was purchased from farmers in the area around the Faculty of Agriculture, National University of Laos. Prior to feeding it was chopped into small pieces and mixed with taro leaf silage and the other ingredients of the diet (cassava root silage and broken rice). The mixed feeds were given to the pigs in 3 meals daily (7:30, 11:30 and 16:30h). Water was permanently supplied through drinking nipples.

Management and feeding

The Mong Cai gilts were mated at third estrus by natural mating with the same Mong Cai boar. The feeding level was at 4% of live weight (DM basis) until pregnancy was confirmed, after which it was restricted to 1.5% of live weight. In the lactation period the gilts were fed increasing amounts up to five days after farrowing, and from then onwards feeds were offered ad libitum.

Measurements

The gilts were weighed at intervals of 2 weeks during pregnancy. They were weighed after farrowing and then every 2 weeks until the end of lactation (42 days). Piglets were weighed at birth and then every 2 weeks to weaning. Feed intake and live weight gain were recorded during the gestation and lactation periods. Litter size at birth and at weaning, birth weight and weaning weight, mortality of the piglets at birth, live weight changes of the sows during lactation, and interval from weaning to oestrus were also calculated.

Samples of taro leaves were taken at the time of ensiling. Samples of water spinach, cassava root and of broken rice were taken for analysis when they were purchased.

Chemical analyses

Feed samples were analysed for dry matter by micro-wave radiation (Undersander et al 1993). Nitrogen and crude fibre were determined according to AOAC (1990).

Statistical analysis

The data were analyzed using the General Linear Models procedure of ANOVA in the MINITAB 13.31 program (2000). Sources of variation were blocks, treatments and error.

Results

Ingredient and chemical composition of the diets

The taro leaf silage and fresh water spinach had DM contents of 20.2 and 8.19 %, respectively, and crude protein (CP) contents of 19.0 and 18.8 % on a DM basis, respectively. The chemical composition of the diets and planned ration formulation are shown in Tables 1 and 2.

Feed and nutrient intake

Feed and nutrient intakes are presented in Table 3 and 4. 

Total DM intake decreased slightly with increased amount of the mixture of taro leaf silage and water spinach. In pregnancy, the daily DM intake was highest in diet TW0 (946 g/day), which was higher (P<0.05) than in the other two diets (910 and 794g/day for diet TW50 and TW100, respectively) (Figure 1).

The CP intake was highest in diet TW0 (85 g/day) (P<0.05) (Figure 2).

In the lactation period daily DM and CP intakes were not different among diets (P>0.05).The proportion of the diet CP derived from the individual ingredients during pregnancy is shown in Figure 3. The protein was supplied almost entirely by soybean meal and the mixture of taro leaf silage and water spinach.

Live weight changes in pregnancy

Live weight changes of the Mong Cai gilts are presented in Table 5 and Figure 4. There were no significant differences among treatments in live weight at service (P>0.05). However, live weights at farrowing declined as the proportion of the mixture of taro leaf silage and water spinach increased (P<0.05). The live weight increase of the gilts in treatment TW0 and average daily gain (ADG) throughout pregnancy were higher than in TW100 (P<0.01).

The length of pregnancy was 114.2, 113.4 and 112.4 days in treatments TW0, TW50 and TW100, respectively (P>0.05). The mean feed conversion ratios (FCR) for treatments TW0, TW50 and TW100 were 3.09, 3.96 and 5.02 kg feed/kg gain, respectively (P<0.01).

Live weight changes of the sows in lactation

Live weight at weaning of the sows was highest in diet TW0 (69.9 kg) and lowest in diet TW100 (56.5 kg) (P<0.05). Live weight loss and percentage of live weight loss in lactation were not affected by the diet (P>0.05) (Table 6).

Reproductive traits

All experimental sows returned to oestrus within around 6 days after weaning, and mean weaning to estrus interval did not differ among treatment (P>0.05).

Piglet performance in lactation

Litter size and piglet live weights at birth, 28 days and weaning are shown in Table 7.