Performance of improved Boran, improved Boran x Sahiwal and Small East African Zebu cattle finished on silage and grass-based rations in Kenya

I Tura¹, P Mwangi¹, F Kemboi^1,2*, O Kashongwe², C Ndung'u¹, V Metto^1,2, P Kaburu¹ and J Kiprop¹

¹ Kenya Agricultural and Livestock Research Organization, Beef Research Institute, Lanet, P O Box 3840- 20100, Nakuru, Kenya
² Egerton University, Department of Animal Science, P O Box 536-20116 Egerton, Kenya
* kemboifred15@gmail.com

Abstract

A hundred and four days of feeding trial of two formulated rations was conducted to determine the dry matter intake (DM), weight gain, feed conversion ratio (FCR) and apparent digestibility coefficients of selected beef breeds in a feedlot system. Twenty-seven (27) beef cattle with an average age of two years, with an initial average body weight of 205 ± 1.3 (mean ± SE) were randomly assigned to two (Rhodes grass and sorghum silage-based) rations and a control group kept under ranching condition in a randomized complete block design (RCBD). Each ration was assigned to three breeds, and each breed was replicated three times. Locally available rangelands feed resources formed the main ingredients in formulation of the sorghum silage and Rhodes grass (Chloris gayana) based rations with minimal addition of maize and sunflower meal to supplement daily energy and protein requirements of growing finishing beef cattle in feedlot system. The metabolizable energy (ME) content of locally available feed resources from the ASALs ranged from 8.7 MJ/Kg DM in Acacia tortilis pods and 14.6 MJ/Kg DM in Balanites aegyptiaca nuts. The crude protein (CP) content ranged from lowest of 84.6g kg^-1DM in Balanites aegyptiaca nuts and highest of 154g kg^-1DM in Acacia tortilispods. Dry matter (DM) for sorghum silage and Rhodes grass-based rations was 87.93 and 89.23% respectively. The metabolizable energy content was 11.06 MJ/kg DM in Rhodes grass based and 12.3 MJ/kg DM in Sorghum silage-based rations. The CP content of Rhodes grass and Sorghum silage- based rations was 15.4 g/kg DM and 16 g/kg DM respectively Dry matter intake was 15.46 kg/day and 10.93kg/day for Rhodes grass and Sorghum silage-based rations respectively. All the experimental diets had a positive weight gain. The average daily weight gain (ADG) was 1.23 kg, 1.201 kg and 0.76 kg for Rhodes grass and sorghum silage-based rations and control group respectively. On the other hand, the feed conversion ratio (FCR) was 12.6 and 9.1 for Rhodes grass and sorghum silage-based rations respectively. There was no significant difference (p>0.05) between ration one and two in terms of average daily weight gain. For the three breeds, the ADG was 1.07 kg for improved Boran X Sahiwal, 0.924 kg for Improved Boran and 0.645 kg for Zebu. Dry matter intake (DMI) was highest in Boran X Sahiwal (13.68 kg/day), followed by Improved Boran (12.62 kg/day) and Small East African Zebu (SEAZ) (10.27 kg/day). The FCR was lowest for Boran X Sahiwal (12.23) followed by Improved Boran (12.87) and SEAZ (13.83). The apparent digestibility of crude protein and dry matter varied across all rations. It is concluded that both rations could be used for finishing beef cattle. It is also concluded that Improved Boran and Improved Boran X Sahiwal are the best suited breeds for feedlot finishing system.

Keywords: apparent digestibility, beef cattle breeds, dry matter intake, feed conversion ratio, weight gain

Introduction

Beef is one of the protein sources for humans, whose demand is on the rise in Kenya (Mwangi et al 2020). With a growing global population, there will likely be a significant increase in demand for beef as an animal protein (Henchion et al 2021). Beef cattle farmers, especially small-scale producers, however, are not able to meet the demand of beef products in Kenya (Mwangi et al 2020). The Arid and Semi-Arid Lands (ASALs) where the largest proportion of beef production is done in Kenya, is characterized by low productivity with over 60% of these areas' inhabitants living below the poverty line of 48% (KNBS, 2019) and subsisting on one dollar per day (Fitzgibbon, 2012). The low productivity could be attributed to feed scarcity due to climate variability, low quality feeds, lack or insufficient knowledge of feed processing techniques, increased livestock diseases and rearing of breeds with low genetic potential in gaining weight (Kahi et al2006; Mudzengi et al 2020; Ndathi et al 2013; Kivunzya, 2019). The population estimates for beef cattle in Kenya is 13.5 M heads (KNBS, 2019). Beef production is mainly from small Eastern African Zebu (SEAZ) animals with a small proportion from commercial exotic/zebu beef animals. Livestock value chain analysis for red meat was done in 2012 and 2014 revealing that Kenya by then had a beef supply deficit of about 100,000 MT and mutton and chevon deficit of about 28,000 MT (Behnke and Muthami, 2011; Farmer and Mbwika, 2012). The current beef demand is estimated to be 705,000 MT (KMT, 2020) and is expected to grow exerting more pressure on the supply chain.

To meet the demand requirements and increase productivity per animal, fattening beef animals using suitable breeds in a feedlot production system could be used as a strategy to maximize body weight gain within a short period. Feedloting is an efficient way of feed utilization since animals are kept in a confined place for meat production only (Malope et al 2007). For ration formulations, local protein sources such as Acacia tortilis pods, Prosopis juliflorapods and Balanites aegyptiaca nuts could be used as ingredients.The afore mentioned protein sources are mainly found in ASALs areas where protein and energy nutrients are scarce, especially in dry seasons. Some energy sources that could be used in rangelands are grass species such as Ex-Tozi, Chloris gayana (Rhodes grass), Eragrostis superba. Enteropogon macrostachus (Bush rye), Cenchrus ciliaris and Chloris roxburghiana (Horsetail grass).These energy sources could also provide substantial amount of protein.

According to Abdulrazak et al (2005); Manhique et al (2017) and Kemboi et al (2017), Acacia tortilis pods, Prosopis juliflora pods and Balanites aegyptiacanuts have a CP of 162g kg-1 DM, 126g/kg and 114g kg ^-1 DM, respectively which is >8g/kg, that is important for rumen function and could spur growth. When combined with energy sources such as sorghum silage and Rhodes grasses, they could be used to prepare rations that will meet the nutritional requirements of beef cattle (Beigh et al 2017). Beigh et al 2017 When fed to the animals, these feeds could assist in the realization of desired daily feed intake and gain. The average daily gain is the major indicator of whether an animal will have a good body weight on sale (Nielsen et al 2013). This paper presents a need to explore on use of feed resources that are locally available for the improved meat output for different breeds of beef cattle in Kenya. This study evaluated appropriate breeds and rations to be used in feedlot system in ASALs to increase meat output, improve offtake and reduce high mortality during dry season, increase household income, with long term outcome in reduced poverty levels among ASALs population.

Materials and methods

Experimental Site

Feedlot trials on the developed rations were conducted in Kenya Agricultural and Livestock Research Organization, Beef Research Institute, Lanet, Nakuru County, Kenya located approximately 150 km northwest of Nairobi, Kenya. It receives an average of 800 mm of rainfall per year. The daily temperatures range between 14 and 26ºC. The Centre is in agro-ecological zones 3 and 4 (Wasike et al 2009).

Preparation of experimental rations

Ration ingredients such as the browse species(Prosopis juliflorapods, Balanites aegyptiacanuts and Acacia tortilis pods)were collected from rangelands of Marigat sub-county in Baringo County, Kenya. After harvesting, the pods and nuts were spread on a sheet and air-dried under shade for seven days. Other ingredients used in the formulation of the two experimental rations were Rhodes grass hay, Sorghum silage, Sunflower Meal and Maize meal. All the ingredients apart from sorghum silage were grounded to pass a 4mm sieve. The rations basal formula was as follows: i) Rhodes grass-based silage and ii) sorghum-based silage. The two rations were formulated according to growing and finishing beef cattle requirements (NRC, 2000). 200 g sample of each of the formulated rations were grounded to pass through a 1mm sieve for proximate analysis.

Laboratory analysis: Proximate assay of samples

Proximate analysis of the feed ingredients i.e., preferred feed supplements used by pastoralists were analyzed to determine their DM (%), CP (g/kg) and ME (MJ/kg).Proximate analysis of sorghum silage and Rhodes grass-based rations were analyzed for dry matter (DM), crude protein (CP), ether extract (EE) and ash according to the standard methods of AOAC (2006). The CP was calculated as Kjeldahl Nitrogen (N x 6.25). Neutral detergent fiber (NDF) and acid detergent fibre (ADF) were analyzed according to the procedure described by Van Soest et al. (1994). The samples of sorghum silage and Rhodes grass-based rations were analysed for Metabolizable energy (ME) by indirect methods as: ME (MJ/kg DM) = 2.20 + 0.1357 × Gas Produced (ml/200 mg DM) + 0.0057 × CP (g/kg DM) + 0.0002859 × EE² (g/kg DM). (Menke, K.H., Steingass, H. 1988).

Selection of experimental animals and data collection

Twenty-seven (27) beef cattle of three breeds viz, Improved Boran, Improved Boran X Sahiwal and small east African Zebu (from Pokot pastoralists) with an initial average body weight of 205 ± 1.3 (mean ± se) were randomly assigned in a randomized complete block design (RCBD) where blocking was done by breed to two (sorghum silage and Rhodes grass-based) rations and a control group was kept under ranching condition. Each ration was assigned three breeds and each breed were replicated three times.

Performance was measured as weight gain on a weekly basis and feed intake was recorded daily. Beef animals were weighed every week after overnight fasting until the completion of the experiment. The feeding trials were conducted for 104 days where the first fourteen days was used for adapting the feeds and 90 days were used for data collection, whereby the three breeds were fed based on 3% of their body weight. Feed offered and refusals were recorded daily and feed intake was calculated by the difference between feed offered and refusal. Average Daily Gain (ADG) was calculated as the rate of weight gain over a specified period. The FCR for each beef animal was calculated by dividing weight gain by feed intake.

Digestibility Trial

The digestibility trial was conducted after 14 days of adaptation to the experimental diet. The total feacal collection for 21 beef animals was done for seven days in the three experimental groups. The daily feacal material collected for each animal was mixed thoroughly and kept in airtight plastic containers. This was followed by drying at 60^oC for 72 hr and then ground and stored in airtight containers pending chemical analysis.

Statistical analysis

Data collected on proximate analysis, feed intake, apparent digestibility, FCR and average daily gain (ADG) were subjected to the analysis of variance (ANOVA) in a randomized complete block design (RCBD) using the General linear model procedure of statistical analysis system (SAS 2002) version 9.0. Significant means were separated using Tukey's HSD (Tukey's Honestly Significant Difference Test) at 5% significance. The linear Model for RCBD used was;

Yij - any observation for which

i is the treatment factor

j is the blocking factor

µ - the mean

Ti- the effect for being in treatment i

Bj-is the effect for being in block

Eij-random error

Results and discussion

Chemical composition

Proximate analysis of ingredients

More than 85% of feed comes from natural pasture and crop residues, but ruminant animal need more feed nutrients to meet their daily feed requirements (CSA, 2020 ). The proximate composition of the feed ingredients is shown in Table 1. The DM content of locally available feedstuff from range lands ranged from 890 g kg^-1DM in Acacia tortilis pods and 940 g kg^-1DM in Balanites aegyptiaca nuts. The CP content ranged from 84.6 g kg^-1DM in Balanites aegyptiacanuts and 154.0 g kg^-1DM in Acacia tortilis pods. The relative high CP content range (84.6 - 154 g kg^-1DM) of Balanites aegyptiaca nuts, Prosopis juliflora pods and Acacia tortilis pods implies that they can be utilized for finishing beef animals in ASALs as protein sources. It is important to note that Prosopis juliflora has been classified as noxious weed by FAO as it is an invasive weed along riverine and areas with high water table and therefore when used as animal feed, it should be ground to break the seeds to prevent propagation in the rangelands. It is also important to note that when grounded, it is hygroscopic in nature thus it has to be used immediately on daily basis to avoid ration spoilage.

The CP of the Balanites aegyptiacanuts, Prosopis juliflora pods and Acacia tortilis are within the recommended range (9-15% CP) of beef feedstuff (NRC, 2007). They can therefore be used in beef rations as ingredients for formulation of rations for beef cattle finishing in ASALs since they have a CP of more than 70 g/kg DM, which is the minimum needed for rumen function according to NRC, (2007). The result of this analysis shows that CP (46.8 g/kg and 53.4 g/kg) and ME (9.9 MJ/Kg and 10.63MJ/Kg) levels for sorghum silage (Lanet forage variety E6518) and Rhodes grass are within the range in FAO Feedipedia (2012). However, Their CP and ME levels for Sorghum silage and Rhodes grass were lower compared to Acacia tortilis nuts and Prosopis juliflora pods which shows high potential of rangeland feed resources to be used as ingredients in beef ration formulation. A study by Abdulrazak et al. (2000) revealed the crude protein content of Acacia tortilispods of 18% while a CP content of 17% as was also reported in Feedipedia (2012). The ME and CP proximate results for Prosopis juliflora pods, Acacia tortilis pods and Balanites aegyptiaca nutsin this study are comparable to recent studies by Tura et al. (2021) and Sagala (2022). Balanites aegyptiaca nuts were high in metabolized energy compared to Prosopis juliflora pods and Acacia tortilis Pods. According to Teshager et al.(2022), the relatively high crude protein content of the locally available indigenous browses (150-249gkg ^-1 DM) provides enough nutrients for utilization as a supplement to low-quality natural pastures and crop residues.

Proximate analysis of rations

Results of the nutrient composition of experimental rations are presented in Table 2. The results in this study show locally formulated Rhodes grass and sorghum silage-based rations could adequately be used to finish rangelands beef animals due to their adequacy in energy (11.06 MJ/Kg DM and 12.30 MJ/Kg), crude protein (15.4 g/kg DM and 16.0) and fibre content. The high NDF in sorghum-based ration could be attributed to delay in harvesting the silage. As NDF content of a feed increases, dry matter intake decreases and chewing activity increases (Haselmann et al 2019). For grass forages, NDF < 50% would be considered high quality and > 60% as low quality (Wassie et al 2018). For legume forages, NDF content below 40% would be considered good quality, while above 50% would be considered poor quality (Tura et al 2021). Ether extract level of this result is within the acceptable range of ruminant nutrition. Ash was high (7.26%) in grass- based ration compared to silage-based ration (5.14%) implying higher mineral contents.

For all the nutrients in the two rations, only NDF and ADF significantly differed (p<0.001). The NDF content in the grass-based ration was below 60% which is an indication of good quality forages except for sorghum based ration which was 71%. This could be attributed to delay in harvesting of sorghum crop for silage making. The indigenous browse species have significant potential in livestock production systems to supplement low-quality feeds (Teshager et al 2022). According to a study by Asmare and Mekuriaw (2019), the indigenous browsing species have tremendous potential in mixed crop and livestock production systems to improve soil fertility, provide fuel and shelter and supplement low-quality meals.

Animal performance on the two rations

Dry matter intake, Average daily gain, Feed conversion ratio and Apparent digestibility

Dry matter intake (DMI)is usually affected by quality of the feed, taste of the feed, smell, processing, fibre levels and anti-nutritive factors among other factors (Mako et al 2021). The DMI for Rhodes grass based and sorghum silage-based rations was 15.45 kg/day and 10.925 kg/day respectively. DMI was higher for Rhodes grass-based ration as compared to sorghum silage- based ration. The high intake in grass-based ration could be due to this ration being ground and prepared into a total mixed ration. The low intake in silage ration cold be due to high fibre levels and was not grounded like the grass. (Rakau et al 2022).

Average daily gain (ADG) for rations 1 and 2 and the control diet was 1.23 kg d^-1 _, 1.20 kg d^-1and 0.76 kg d^-1_,respectively (Table 3). The ADG was not significantly different for ration one and two, however, significant difference was observed in the control diet. The ADG being lower for the control diet as compared to Rhodes grass based and sorghum silage-based rations could be attributed to the animals in the control group utilizing more energy while in the ranch in search of forage compared to the confined animals which were being fed on the two formulated rations (Senturklu et al 2021). It could also be due to poor quality grass such as wire grass (Aristida stricta) dominating a larger portion of the ranch.

Feed conversion ratio (FCR) for rations 1 and 2 Rhodes grass and sorghum silage-based diets were 12.6 and 9.1 respectively. The FCR was significantly different between rations 1 and 2 (Table 3). The lower FCR for ration two compared to ration one indicates that the nutrients in silage based were efficiently utilized compared to ration one viz, Rhodes grass based (Gage and Mummed, 2021). This is because the lower the ratio, the better the feed is utilized (Vorlaphim et al 2021). Feed conversion in ruminants is influenced by both the animals' capacity for nutrient absorption (genetic potential) and utilization as well as the capacity of the rumen bacteria to ferment the components of their diet to form volatile organic acids (Lopes et al 2021).

The apparent digestibility of crude protein and dry matter varied across all diets. Apparent digestibility coefficient provides estimates of nutrient availability in feedstuffs and is used to select ingredients that enhance nutritional value (Fagbenro, 1999). The differences in apparent digestibility coefficient of ingredients may be explained by differences in chemical composition, which is determined by the processing or origin of the feed ingredients (Köprücü and Özdemir, 2005). Balanites aegyptiaca nuts, Prosopis juliflora pods and Acacia tortilis pods significantly improved the intake, digestibility and ADG as shown by the results (Table 3). Therefore, these rangeland feed resources can be used as a source of CP and ME to replace use of commercial feeds in arid areas where accessibility of commercial feeds is limited. (Mudzengi et al 2022).

Breed effect on animal performance on the two rations

Average daily gain, Dry matter intake, Feed conversion ratio and Apparent digestibility

The suitability of breeds in terms of adaptation to the existing environment and the potential of the animal to increase its daily weight gain is of great importance (Norris, 2002). Purebred and cross-bred beef animals can affect the potential of an animal to gain weight (Norris et al 2002). This is because different animals can gain weight at different rates depending on their breeding systems (Muižniece and Kairiša, 2016; Zimmermann et al 2021). This study evaluated how the three beef breeds efficiently utilised and converted the two rations (Rhodes grass and silage-based rations).

The ADG for Improved Boran, Improved Boran X Sahiwal and Zebu were 0.92 kg, 1.06 kg and 0.65 kg respectively. The ADG was highest for Boran X Sahiwal followed by Improved Boran and small east Africa Zebu for both rations. Improved Boran and Sahiwal have been selected and bred over time to improve breed efficiency in terms of daily weight gain, but Small East African Zebu cattle used in this experiment were purchased from Pokot pastoralists in East Pokot.

The result of this study revealed that pastoral Small East African Zebu is less efficient in feed conversion compared to other breeds. The ADG for small east African Zebu was almost comparable to results (0.53kg) found by Magana and Sagana-correau (2005) although this was obtained at the age of 18 months. In a study done by Asimwe et al (2016), Zebu cattle under feedlot system for 100 days gained an average daily weight of 0.88 g. A lower average daily weight gain of 0.71 kg was obtained in Ethiopian Borana for bulls which were fattened for ninety days in Musa et al (2022).

The DMI for Improved Boran, Improved Boran X Sahiwal and Zebu were 12.62 kg/day, 13.68 kg/day and 10.27 kg/day respectively (Table 4). These results showed that higher body weight determined high feed intake viz, the bigger the animal in terms of live weight the more feed they tend to consume. It was also observed that the small East African breed rounded up earlier compared to Improved Boran and Improved Boran X Sahiwal crosses. The three breeds were fed the rations based on 3% of their body weight on daily basis and at the end of the experiment it was observed that crosses still needed more time to round up due to their larger body frames. It is recommended therefore that crosses may be fed at up to 4% of their body weight to be finished in 90 days or their finishing be extended for a longer time like for 120 days.

Feed conversion ratio (FCR) is the amount of feed required to gain one unit of gain and a lower number is desirable (Lamb et al 2013). It is the most common measure of feed efficiency in animal nutrition (Lamb and Maddock, 2009). Feed conversion ratio is also a ratio of measuring efficiency with which the bodies of livestock convert animal feed into the desired output.The FCR for Improved Boran, Improved Boran X Sahiwal and Zebu were12.87, 12.23 and 13.80respectively. A feed conversion ratio of up to 7.93 was reported in for short horned zebu bulls in a feedlot (Msalya and Mpenda, 2022). An almost comparable FCR value of 8.47 and 9.94 has been observed in Harar oxen under feedlot conditions (Gage et al 2022). The results of this study showed that Improved Boran X Sahiwal were good converters, followed by Improved Boran and Zebu, although the FCR for all the breeds were not significantly different. Therefore, the results of this study indicates that crosses and improved Boran are more efficient animals because of their size for finishing beef animals in feedlot system.

Conclusion

• Local rangeland feed resources such as Prosopis juliflora pods,Acacia tortilispods and Balanites aegyptiaca nuts and fodder sorghum which are found in the ASALs can provide sufficient nutrients (CP and ME) to growing beef cattle in the feedlot production system. It is recommended therefore that these local fodder trees could be conserved and propagated for sustainable use in feed formulation.
  
  
• The invasiveness of other tree species such as J. juliflora could be managed by proper utilization and not by elimination as requested by pastoral communities.
  
  
• The results of this study revealed that finished Improved Boran X Sahiwal and Improved Boran steers attained a higher daily weight gain and efficient feed utilization from the two formulated rations as compared to the small east African Zebu. This study therefore recommends that both Improved Boran X Sahiwal and Improved Boran breeds are most suitable for beef finishing in feedlot system for the recommended period of 90-120 days.

Acknowledgment

The authors are grateful to Kenya Climate Smart Agriculture Project (KCSAP) for financial support and The Director General, Kenya Agricultural and Livestock Research Organization (KALRO) for logistical support, KALRO - Muguga for laboratory and Egerton University, Animal Science Department for laboratory analysis. We acknowledge technical support from N.K. Kibitok for in-vitro digestibility analysis.

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