Effect of dietary protein levels on growth and feed conversion of native pigs (Sus Scrofa) fed a mixture of ensiled taro foliage and cassava root meal

Tran Trung Tuan^1,2 and T R Preston³

¹ An Giang University, An Giang, Vietnam
tttuan@agu.edu.vn
² Vietnam National University Ho Chi Minh City, Vietnam
³ Centro para la Investigación en Sistemas Sostenibles de Producción Agropecuaria (CIPAV), Carrera 25 No 6-62 Cali, Colombia

Abstract

Twenty native pigs, with an average initial live weight of 10.3 kg were used in a 56-day growth experiment and were housed in individual pens and randomly allocated to 5 dietary crude protein levels (10, 11, 12, 13 and 14% in DM), derived from ensiled taro foliage (Colocasia esculenta) and cassava root meal. There were positive trends in all performance traits with linear increases in feed intake and live weight gain and improvements in feed conversion with optimized results at 14% crude protein in the diet DM, 92.5% of which was derived from ensiled taro leaves and petioles. Moreover, from the farmers’ point of view, the economic advantages of unvaluable crop byproduct was used in pig productions (indigenous breeds) to improve income and also reflects one way in which feeding systems can be developed with benefits, however small, to counter global warming and lost of biodiversity in agricultural systems.

Key words: local feed resources, indigenous breeds, protein-rich forages

Introduction

Some farmers grew taro (Colocasia esculenta) for the edible corm as a starch source for people food and crop along with rice planting for family income in Viet Nam. After 5 to 6 months of vegetation period when about 60% leaves defoliated, taro corms were harvested and foliage left behind and burned in the field. According to Lampheuy et al (2012) taro foliage proportion average accounted for 52 to 62% and the leaves contained greater CP and CF than petioles; and total essential amino acids (arginine, histidine, isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tyrosine and valine) ranged from 40.5 to 42.5g/16gN.

Antinutritional factor such as calcium oxalate contained high, about 780 mg per 100g in some species of taro and it caused irritation or acridity. Oxalate also tends to precipitate calcium and makes it unavailable for use by the body (FAO, 1990). According to Hang et al (2011 and 2013) oxalate content in leaves and petioles of taro cultivars can be reduced effectively by ensiling. Therefore, taro foliage will be a supplementation of calcium source for animals when appropriate process before feeding to animals such as ensiled or boil taro foliage.|

Native pig origin was from highland central provinces of Viet Nam. Native pig had a small size with average mature weight at about 6 months was 35 to 45 kg. The pigs had a good ability to adapt with diseases resistance, harsh environment and poor nutritive feedstuff (Duc, 2018). The first oestrus, mating and farrowing of pig ranged from 216 to 221days, 241 to 248 days and 355 to 372 days, respectively; and average daily gain for a boar was 209 g/day and 201 g/day for a gilt in the period of 2 to 8 months (Cuc et al, 2020).

The aims of the experiment were to determine the protein levels needed to optimize growth rates in Native pigs when the protein source was supplied from ensiled taro foliage (Colocasia esculenta) and contributed small to agricultural biodiversity by using unvaluable feedstuff to feed pigs.

Materials and methods

Treatments and experimental design

Twenty native pigs, with average initial live weight of 10.3 kg were housed in individual pens and randomly allocated to 5 dietary levels of crude protein: 10, 11,12, 13 and 14% in DM, derived from ensiled taro foliage and mixed with cassava root meal (Table 1).

The experiment was designed as a Randomized Complete Block with 5 treatments and 4 replications. The pigs were allocated to blocks based on initial live weight and at random within blocks according to treatment. The experiment was conducted over 56 days. Samples of ingredients (Table 2) were analyzed for DM, crude protein, crude fiber and ash according to the standard methods of AOAC (1990), Dry matter was determied by using microwave radiation (Undersander et al 1993).

Animals and management

Twenty (10 castrated male and 10 gilts) native pigs with average body weight at 90 days of age were 10.3 kg be used to conduct in the experiment from a private farm in An Giang Province. All pigs were vaccinated against hog cholera and foot and mouth disease and were treated against round worms before starting the experiment.

The pigs were housed in individual pens (1.2 m x 1.2 m) made of woods with feeding troughs to allow recording of offered feed and to collect refused feed. The pigs were given feed ad-libitum four times per day at 07:00, 11:00, 14:00 and 17:00h and feed refusals were collected and weighed before the morning and afternoon feeding. All pigs had free access to water with nipple drinkers. The experiment was conducted in a private farm in An Giang province.

Processing taro silage and experimental diets

Taro leaves and petioles were collected from the field after farmers had harvested the tuber and were chopped into small pieces (2 to 3 cm) and wilted under sunlight for 2 days to reduce moisture. Before making the silage, all pieces of taro leaves and petioles mixed with rice bran and molasses following the formula 90: 5: 5 ratio and put in plastic bag tightly to reduce the air and fermented for 7 days. The diets were based on ensiled taro foliage and cassava root meal; and were formulated to contain level of 10, 11, 12, 13 and 14% crude protein in DM.

Photo 1. Taro field	Photo 2. Collected taro foliage
Photo 3. After 2 days sunrised	Photo 4. Ensiled taro foliage at 7 days
Photo 5. Native pig in 10% CP diet	Photo 6. Native pig in 14% CP diet

Statistical analysis

The data for feed intake, growth rate and feed conversion ratio were analyzed as a Randomized Complete Block Design by using the General Linear Model (GLM) of the Analysis of Variance (ANOVA) procedure of the Minitab statistical software release 16. Sources of variation were animals, treatments, blocks and error. Polynomials were fitted to the performance data using software in Microsoft Excel.

Results and discussion

Ingredients and chemical composition of the diets

Chemical composition of ingredients showed in table 2. At 7 days of ensiled taro foliage, pH was slightly higher than the results from Hang et al (2018) when ensiled taro with rice bran or molasses.

The composition of the diets and crude protein levels in the experimental diets achieved in the final mixtures were close to the planned levels (Table 3).

Feed intake, growth rates and feed conversion

All criteria included the data for daily feed intake, growth rate and feed conversion ratio showing that were responded an optimization when crude protein concentrations approached 14% in the diet DM and followed the curvilinear trends (Table 4; Figures 1-4). The crude protein content was increased across diets and higher than the level of 12% in DM reported as optimum for growing Moo Lath pigs fed diets based on ensiled taro foliage (Sivilai et al 2017) and was similar to the level of 14% in the diet reported from Tuan et al (2021) when native pigs fed replaced diet of soybean meal by ensiled taro foliage. Moreover, the data for feed intake and gain weight were higher and feed conversion was lower than the results from these authors.

Figure 1. Effect of dietary protein concentration on DM intake	Figure 2. Effect of DM intake on live weight gain

Figure 3. Effect of %CP in diet DM on live weight gain	Figure 4. Relationship between dietary protein concentration and DM feed conversion

Moreover, the results were also evaluated from the economic and environmental viewpoint. In this respect, the economic advantages of unvaluable crop byproduct was used in pig productions (indigenous breeds) to improve income, especially in rural areas and small, the environmental benefit was reduction in global warming from burning crop byproduct by it’s utilization in pig production and contributed to improve biodiversity in agricultural system.

Conclusions

• Native pigs over the live weight range 10-25 kg fed forage-based diets containing 92.5% of forages in the form of ensiled leaves and petioles of taro were optimized growth and feed conversion at 14% crude protein in the diet DM.
• A locally produced byproduct also reflects one way in which feeding systems can be developed with benefits, however small, to counter global warming and loss of biodiversity.

Acknowledgements

The author wishes to thank Mrs. Nhien, pig farm owner who sponsored all materials to conduct the experiment and Mr. Tung who help to take care of the feeding and management of animals.

References

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