Wet brewery yeast as an alternative feed resource for weaned pigs

L C Mwaipopo, W S Nyitika, G K Mutabazi, A E Mwakipesile and S H Dawite

Tanzania Livestock Research Institute (TALIRI-Uyole) P O BOX 6191, Mbeya, Tanzania
mwaipopol@yahoo.com

Abstract

An experiment was conducted at Tanzania Livestock Research Institute (TALIRI Uyole) to assess the growth performance of weaned pigs when fed diets containing wet brewer yeast (WBY) as a protein source. The diets were formulated to replace fish meal and contained different percentages of WBY (0%, 10%, 20%, and 30%). The experiment lasted for 12 weeks, during which the weaned pigs were fed the different diets. At the end of the 12-week period, the results showed that weaned pigs fed a diet containing WBY at 10% had a higher growth rate than those fed diets with higher or lower percentages of WBY (p<0.05). Additionally, male pigs had a higher growth rate than female pigs. Based on these results, the researchers concluded that WBY could be used as an alternative source of protein in rural pig production systems, particularly for smallholder farmers. This finding suggests that using WBY in pig diets could be a viable solution to the challenge of expensive and limited feed resources faced by small-scale pig farmers on top of that avoid air pollution in the disposing area which is of public concern in the study area as its disposal is often an environmental problem.

Keywords: compounded diets, growth rate, wet brewery yeast, pig

Introduction

Pig production is emerging as one of the fast-growing rural economic activity in East and Southern African Countries (ESA). Pork is the world’s most widely eaten meat accounting for 40% of total meat eaten. Second to pork is chicken (29%), followed by beef (24%), turkey (2%) and others (5%) (FAO 2012). In Tanzania rural areas there is a significant number of individual households engaging in pigs rearing activities, where over 1.9 million of pigs are kept. Mbeya harbors 36% of pigs available in Tanzania (NBS 2016/2017). Smallholder farmers in rural areas rear most of these pigs and it is contributing about 5-10% to household income in these areas (Kamaghe et al 2014), food, and manure for crops production and in some areas, manure is a source of energy through biogas (Chimanyo et al 2005). In the tropics, pigs grow at the rate which is half of the recommended rate; and this is highly contributed by low level of feed resources (NRC 1988). Most feed resources (mainly protein and starch) are competitive and more expensive. A visit made by TALIRI team to Tanzania brewery company Limited (Mbeya Plant) gave new insight on how to use some industrial by-products to tackle nutrients challenges such as high cost of protein and important minerals facing pig industry in the country. The plant manager enlightened on how they dump significant amount of spent brewer’s yeast into sewers while this by-product is feed resource rich in protein, vitamins and minerals, which if judiciously used can be used as protein source in pig diets and poor utilization of this by-product is a serious source of environmental pollution when there is unproper disposal of it.

According to Ferreira et al (2010), brewer’s yeast contains about 50% DM, Crude protein between 40-56%, and is an important source of vitamins, nucleic acids and minerals hence can be utilized well in pig production. To avoid growth of yeast in the intestinal tract, which may in turn cause competition for nutrients between the live yeast and the animal itself the yeast is inactivated, Inactivated brewer’s yeast is a highly valuable source of protein, phosphorous and vitamin B (Crawshaw 2004). Despite of the potential for brewer yeast to feed cattle, pig, and poultry; all spent brewer yeast produced at TBL (Mbeya plant) is dumped into sewer. However, observations made by Van Enckevort and Gobius du Sart (2007) suggested that, including spent brewer’s yeast in pig diet led to high average daily gain in pigs. Furthermore, according to Blair (2007), spent brewer’s yeast can be replaced up to 80% of protein in diets. Furthermore, few farmers close to Mbeya plant have started using this product to different classes of pigs and other livestock. However, they lack proper information on feeding level of this product and its management. In this context, the need for improving availability, accessibility and utilization of locally available feed resources particularly brewery yeast for pig production in Tanzania is inevitable. Hence the aim of this study was to evaluate the effects of replacing of fish meal by brewers’ yeast extract on growth performance of diet of weaner pig.

Materials and method

Study Location

The experiment was conducted at the Tanzania Livestock Research Institute (TALIRI), Uyole. TALIRI Uyole is located at Uyole, about 10 km from Mbeya City center with an altitude of about 1850 meters above sea level. It lies between latitudes 08.92044’ – 08.92011’ S and Longitudes 33.54053’ – 33.53063’ E. The Centre renders its services in the Southern Highlands Zone comprising of six regions (Iringa, Mbeya, Ruvuma, Rukwa, Katavi and Njombe). The Zone is situated between Latitudes 7◦ and 9◦ S and Longitudes 30◦ and 38◦ E with altitude and annual rainfall varying between 475 and 3000 meters above sea level and 600 to 2600 mm per annum, respectively.

Housing and management of animals

Twenty-four (24) weaned pigs of 3 months weeks of age were randomly penned in eight (8) concrete floor pens (4 females and 4 males’ pens) with each pen having three (3) pigs.

The average weight per pig at the start of the experiment was 9.9± 0.2 kg. Seven days prior to experiment, experimental feeding period was allowed to enable experimental animals adjust to the experimental diets. The animals were marked for individual identification with permanent marker also all pigs were dewormed and all animals’ welfare standards were adhered.

Management of Wet Brewery Yeast products

Inactivated brewery yeast was collected from Tanzania breweries Company (Mbeya plant) in plastic container. Allowed to settle to enable alcohol and water to be removed from the container and left with porridge material. This porridge remains which is WBY was used to formulate the experimental diets on daily basis to avoid food spoilage as the material is ease to be spoiled.

Feeding of experimental animals

During feeding, wet brewery yeast ration were fed ad-libitum at a rate of 10% WBY 20% WBY and 30% WBY of the compounded diets respectively replacing fish meal. The feed rations were formulated from maize bran, maize meal, sunflower seed cake, fish meal, Wet Brewery Yeast (WBY), bone meal, limestone and pig mix. The treatments (WBY10 to WBY30) diets with wet brewery yeast were used as a source of protein and one treatment diet without WBY labelled WBY0 used as a control were formulated comprised more fish meal (3 kg) and other feeds ingredients as it is shown in Table 1. The amount of concentrates (WBY0 to WBY30) offered to pigs ranged from 0 to 30% WBY varying within treatments. The pigs were fed twice a day at 8:00h and 3:00h to avoid spill over from feeding troughs and water was given ad-libitum.

Results of the analysis show that the CP contents of the four compounded diets ranged between 17.6 – 18.5% and were above recommended level (15-16%) for growing pigs.

Experimental design and data collection

Experiment pigs were blocked according to sex and assigned to four dietary treatments. A randomized block design was used with four treatments which were combination of maize bran, maize meal, sunflower seed cake, fish meal, WBY, bone meal, limestone and pig mix in a ratio, as explained above (Table 1). Feeds were weighed prior to feeding. Refusal were collected and weighed the following morning. The difference between feeds offered and refusal indicates the voluntary dry matter intake of all basal diets. Proximate analysis of dietary feeds was done to determine the dry matter (DM), crude fibre (CF), crude protein (CP) ether extract (EE) crude fat (CF) and ASH according to the procedures of (AOAC 2003). Body weight measurement was taken at the onset of the experiment to monitor growth performance and this was done once per week for 90 days, while monitoring health status of the pigs during the experimental period.

Statistical analysis

The data collected on feed intake and growth rate were subjected for analysis of variance (ANOVA) using General Linear Model procedures of SAS for completely randomized block design. Model sums of squares were partitioned to test P-Values for linear trends; the following model was employed.

Yij = µ+Ti+ ej

Where; Yis the dependent variable μis the overall mean and Tiis the effect of treatment (i=1, 2, 3, 4) eis the random error term

Results and discussion

Health status of experimental animals

All pigs were in good body conditions from the setup of the trial to the end of the trial.

Feed acceptance consumption

The formulated diets with different level of Wet brewery yeast (WBY) were well accepted (99%) by the experimental pigs and the refusal amount were negligible.

Growth performance

Least Square Means (LSM) showing growth performance of all four dietary treatments for (WBY0, WBY10, WBY20 and WBY30)  in Table 3

Table 5. On the last week (week 12) pigs under treatment (WBY10) was characterized with higher growth rate.

At the end of the trials experimental animals fed WBY10 showed high growth rate, followed by WBY20 and Average Dairy Gain (ADG) shown by WBY10 was higher (227.7 g/d) compared to other treatments. From the trials results it is evident that WBY can be included in the pig diets and be utilized well (higher feed intake and support moderate growth rate as all diets contained WBY had higher growth performance than diets without brewery yeast.

Figure 1. Response daily gain against % Wet Brewery yeast in the diets

Figure above shows the response curve top live weight gain at 10 % of WBY in the diet. There is an improvement in growth rate at low levels of WBY and this trend begins to decrease in response with highest level of WBY.

Discussion

Under rural pig production systems farmers mainly utilize mostly locally available feed resources and feeding strategies to reduce feed costs as a cost structure of feeding pigs accounts over 70 to 80% of cost of production (TOMAK 2017). The use of local feedstuffs may have also due to unavailability of commercial feeds and associated costs. In most cases smallholder have limited financial resources hence is a limitation to engage in profitable pig farming (Muhangi et al 2014; Ouma et al 2014). Results from present study indicated the use of WBY had an effect on growth performance of weaned pigs which conform to other study, (Zhang et al 2019) reported that yeast hydrolysate enhanced the digestibility of feed in growing-finishing this is a factor that could explain the superiority of brewers’ yeast extract compared with combined fish meal and soybean meal as a protein source. Suzuki et al (2018) in Japan reported the effects on growth of finishing pig, (White et al 2002) differ with this result as reported that feeding weaned piglets on feed supplemented with 3% dried Brewery Yeast significantly decreased feed intake and body weight gain. In the other study, by Suzuki et al (2018) finishing pigs fed with 15% of Liquid Brewery Yeast mixed (9.75% in terms of dry matter), and there was no difference in feed intake and body weight gain when compared with the control group. On this experiment study the feed containing WBY had higher growth performance compared to control group, the reason for underperforming of WBY may be related to genetical variations of tested pig in tested trials or high amount of alcohol in the Liquid brewery yeast also can influence the results. Kabugo et al (2014) reported pigs fed Spent brewery yeast (SBY) 6% were able to attain higher ADG than diets with 8% and 10% SBY which conform to result reported elsewhere by Van Enckevort and Gobius du Sart (2007). In addition it was also noted variation on the liveweight where female pigs had lighter weight compared to male pigs, this variation can be contributed by many factors as genetical factors as noted by Campos et al (2012), low birth weight of many female pigs (Peterson 2008), and variation on weaning age (Main et al 2004). This variation is inherent and, in most cases, is hard to manage.

Conclusion

The study found that WBY is safe for use in pig formulated diet (rations) when just 10% of diets fed had no effects and showed high growth rate and feed intake rate was good 99%. All diets with WBY % had higher growth rate than control diets, WBY are cheap protein source for pigs as it can be centrifuged or changed into dried form and fed to pigs to replace fish meal because feeding WBY is tedious as you have to formulate the diets every day to avoid food spoilage.

Acknowledgments

Authors acknowledge the financial support from Tanzania Breweries Company (TBL Mbeya-Plant).

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