Effect of feeding different proportion of Urochloa mutica and natural grass hay as a basal diet on feed intake, milk yield and composition for lactating Jersey cows in Ethiopia

Tamene Tadesse^1,2, Ajebu Nurfeta¹ and Adugna Tolera¹

¹ School of Animal and Range Sciences, College of Agriculture, Hawassa University, P O Box 05, Hawassa, Ethiopia
tametade2011@gmail.com
² Department of Animal Sciences, College of Agriculture and Natural Resource, Assosa University, P.O. Box 18, Assosa, Ethiopia

Abstract

This experiment was planned to evaluate feed intake, milk yield and composition of lactating Jersey cows fed on different proportion (0:52, 17:35, 35:17, and 52:0%) of Urochloa mutica (Forssk.) T.Q. Nguyen and natural pasture hay as a basal diet supplemented with commercial concentrate mixture (CM). Four purebred Jersey dairy cows (average age of 4±0.38 year) in second parity with milk production of 8 to 10 kg day^-1 were allocated to treatments in a 4×4 latin square design. The treatments involved 52% natural grass hay (NGH) + concentrate mix (CM) (UM0); 35% NGH + 17% U. mutica (UM) + CM (UM17); 17% NGH +35% UM + CM (UM35) and 52% UM + CM (UM52). The highest ( p< 0.01) dry matter (DM) intake was for cows fed UM52 followed by UM35. Likewise, cows fed UM35 and UM52 had higher (p< 0.01) organic matter (OM) and crude protein (CP) intakes than those fed UM0 and UM17 diets. Dry matter, OM and CP intakes increased (p<0.01) as proportion of U. mutica hay increased, with higher intake for cows fed UM35 and UM52 than cows fed the remaining treatment diets. The highest (p< 0.01) average daily milk yield was observed for cows fed UM52 whereas, the lowest was observed for those fed UM0. Daily fat-corrected milk, lactose, protein yields, feed efficiency and body condition scores increased (p< 0.01) as the level of U. mutica hay increased in the basal diet. Hence, it was concluded that in lactating jersey cows, 52% inclusion of U. mutica in a basal diet increases dry matter and nutrient intake, resulting in higher milk yield.

Key words: body condition score, feed efficiency, milk production, milk fat, nutrient intake

Introduction

Increasing ruminant livestock populations in many areas of the sub-Saharan Africa have increased the demand for land for fodder production. Traditionally, mixed crop-livestock agriculture is feasible where the management facilitates reciprocal nutrient and energy flows between crop and livestock components with minimum demand for external nutrient supply (Andrieu et al 2015). The mechanisms for reciprocation include the use of crop residues as animal feed, animal waste in integrated soil fertility management, animal draught in farm mechanization, fodder grasses and legumes for erosion control, legumes for biological nitrogen fixation and reduction of greenhouse gas emissions, and promotion of reforestation using multipurpose fodder trees. However, this synergy is compromised when farmers are confronted with competing interests between land use for food or fodder crops; and between crop wastes for mulching and livestock feed (Homann-KeeTui et al 2015). The major problems affecting livestock productivity in the mixed crop- livestock production systems in Ethiopia are feed availability and quality. Land available for livestock feed production becomes limited as more land is being shifted to crop cultivation. The nutritional requirements of heifers, dry, pregnant and lactating cattle for milk production are not sufficiently met. Under such conditions, cows in early lactation and high producing cows are typically in a negative energy balance. As a result of decline in the yield and nutritive value of tropical grasses mainly during dry season (Babayemi et al 2009), there will be reduction in feed intake, greater weight loss, and milk production (Smith 2001). Farmers retain female calves to replace culled cows in spite of the additional stress on limited feed resources during the dry season (Mohd Nor et al 2015).These indicates the need for cultivated fodder for sustainable intensification.

Urochloa grass is a multipurpose grass for feed with land sparing because it produces high biomass on small size of the land. It is also a key rotation component for control of stem-borer of maize (Pickett et al 2014). In addition, it reduces nitrous oxide emission from the soil through biological nitrification reduction (Subbarao et al 2009). The CP content of Urochloa grass ranged between 9.7-12.8 % (Nguku et al 2016) and there is an indication that palatability and response of animal improves when Urochloa grass is fed (Rao and Ghimire 2016). The intake of Urochloa grass was poor, but improved the CP and ME intakes with increased milk yield when supplemented with Desmodium intortum hay (Mutimura et al 2018). Hence, utilization of Urochloa grass as a livestock feed is not optional and is increasing from year to year in east Africa (Mutimura and Everson 2012; Djikeng et al 2014; Mutimura and Ghimire 2021). The use of Urochloa grass as animal feed could play an enormous role because it is drought tolerant, fast recovery after grazing, high plant vigor and produce more forage biomass and quality (Worku et al 2021; Tadesse et al 2023). Urochloa grass is important constituent of natural vegetation across sub-Saharan Africa which grows well in different agro-ecological zones of tropical Africa (Rao and Ghimire 2016). The grass cultivars were introduced, evaluated and preferred by farmers in eastern Africa (Mutimura and Everson 2012; Djikeng et al 2014; Mass et al 2015). U. mutica is nutritious and produces a high yield of forage per hectare (Zemene et al 2020; 12.43 t/ ha; Aysheshim et al 2022; 11.8 t/ ha).

Urochloa grasses have potential to increase feed intake, digestibility and milk yield in dairy cattle (Mutimura et al 2016; Schiek et al 2018). Though information regarding the effect of the inclusion of different proportion of Urochloa grass, particularly Urochloa mutica in the basal diet on the performance of dairy cows is limited, previous research showed that the of sole Urochloa grass resulted in higher DM intake and 33% more milk in lactating cows than sole urochloa grass (Mutimura et al 2018). The grass is currently used as livestock feed in Ethiopia. Studies conducted on small ruminants showed the used of increased proportion (from 0 to 100%) of Mulato II hay in the basal diet increased feed intake and body weight in sheep (Adnew et al 2021). This study hypothesize that Urochloa mutica could be included in a basal diet of Jersey cows and Urochloa mutica would be superior over natural pasture grass in feed intake, milk yield and milk composition. Hence, this study was undertaken to evaluate feed intake, milk yield and composition, feed efficiency and body condition scores of Jersey cows fed on different levels of U. mutica and natural grass hay supplemented with commercial concentrate mixture.

Materials and methods

Study area description

The study was conducted at Wolaita Sodo Dairy Cattle Breeding Center, which is located between 1600 and 2200 meters above sea level (6°55’N and 37°45’E), southern Ethiopia. It receives an average annual rainfall of 1272 mm and minimum and maximum temperatures of 15^oC and 25^oC, respectively (Tadesse et al 2023). The study area is categorized by bi-modal rainfall, short rainy season (between February and May) and main rainy season (between June and September) (IFPRI 2006). The soil at Wolaita Sodo dairy farm was a silt clay loam, slightly acidic (Tadesse et al 2023).

Experimental animal management, design and treatments

Four early lactating (88 ± 24 days after calving) purebred Jersey cows with average body weight of 401±29 kg and average age of 4±0.38 year in second parity producing 8-10 kg/ cow/ day of milk, were selected from Jersey dairy herd at Wolaita Sodo Cattle Breeding Center. They were stall-fed individually in a well-ventilated barn with concrete floor and appropriate drainage slope. Fresh water was available all the time. They were provided ivermectin for external and treated with tetraclozan for internal parasites before the start of the experiment.

A 4 × 4 single Latin square experimental design was implemented. The experiment consisted of 4 treatments and 4 periods; the experimental cows were assigned to each one of the four treatments. Each Latin Square period involved 22 days; with the first 15 days for adaptation to the treatment diets to remove the carry-over effects and the remaining 7 days for the sampling and actual data recording. The total duration of the experiment was 88 days.

The four roughage-based dietary treatments supplemented with concentrate mixture were: Natural grass hay (NGH) 52% + concentrate mix (CM) (UM0); 35% NGH + 17% U. mutica (UM) + CM (UM17); 17% NGH +35% UM + CM (UM35); 52% UM + CM (UM52). For this study, the iso-caloric and iso-nitrogenous treatments (Table 1) were formulated according to the NRC (2001) to satisfy the ME and CP requirements of a lactating cow weighing 454 kg producing 10 kg day^-1of milk with 5 % fat at 52:48 roughage to concentrate ratio. The proportion and chemical composition of feed ingredients are shown in Table 1.

Baled hay of natural grass was purchased from Sululta and composed of a mixture of mainly Cynodon, Digitaria, Andropogon and Panicm grass species with some native legume (Trifolium species) (Yalew et al 2020). Urochloa mutica (Forssk.) T.Q. Nguyen was selected over the other Brachiaria cultivars for its high CP content, biomass yield, drought tolerance, resistance to spittlebug, fast recovery following defoliation, easy for establishment and adaptation to well-drained, acid tropical soils (Argel et al 2007; Mutimura et al 2017; Mutimura and Ghimire 2021). U. mutica was planted in accordance with the recommended agronomic practices (Ben et al 2018) on 2 ha at Wolaita Sodo Dairy Cattle Breeding Center. It was supplemented with irrigation to support continuous growth for sufficient biomass production. U.mutica forage was manually harvested and air-dried under shade. For appropriate drying, it was turned every day for a week until it was well dried. Both U. mutica and natural pasture hays were manually chopped into 5 cm length using machete, and mixed thoroughly before feeding. The basal feeds were fed ad libitum (adjusted at 20% refusal) separately in the feeding trough. The formulated concentrate mixture composed of maize (Zea mays), noug (Guizotia abyssinica) seed cake, wheat (Triticum aestivum) bran, limestone and salt was purchased from Damota Wolaita Farmers, Animal feed processing cooperative, Sodo, Ethiopia. Maize grain and noug seed cake were used to make the supplements iso-caloric and iso-nitrogenous, respectively, across the treatments. Each feed ingredient in the concentrate were measured daily and mixed thoroughly for each treatment and fed at 07:30 and 16:00 h per day. The amount of supplement varied between 5.8 to 6.1 kg/ d among the treatments to make the supplement isocaloric and isonitrogenous. Feed samples were collected daily and pooled by feed type, during the data collection period. Likewise, samples of feed refusals were collected daily and pooled by the cow for each period. Representative samples from each feed type and refusal for every cow were taken for laboratory analysis.

Milk sample analysis, feed efficiency and body condition scores

Daily milk yield was measured twice a day. Milk samples (50 mL) were collected twice a day at 07:00 and 15:30 h during the last 7 days of each period using a graduated cylinder. The samples were kept in ice box, transported to the laboratory, blended using a magnetic stirrer. The duplicate samples for each milking were analyzed daily using a LactoScan milk analyzer (Milkotronic Ltd., Nova Zagora, Bulgaria) and daily average value for milk fat, protein and lactose were determined for each cow. Fat-corrected milk yield (kg/d) = 0.4 × Milk production + 15 × (% Milk Fat/100) × Milk Production (NRC 2001). Feed conversion efficiency was calculated by dividing FCM by DM intake. Body condition scores (BCS) were taken at the beginning and end of each data collection period, after 15 days of adaptation period based on the scale described by Heinrichs et al (2023).

Chemical analysis

The samples were dried in a forced-air oven at 60^oC for 48 h and ground to pass through a 1 mm sieve using Wiley mill (Thomas Scientific). The DM (dry matter) and ash were analyzed according to AOAC (2005). Neutral detergent fiber (NDF) and acid detergent fiber (ADF) were determined according to Van Soest et al (1991) using an ANKOM 220 Fiber Analyzer (ANKOM Technology, New York, NY, USA). Acid detergent lignin (ADL) was determined according to Van Soest and Robertson (1985). Nitrogen (N) content was determined by the Kjeldahl method (AOAC 2005), and crude protein (CP) was calculated as N×6.25. The milk composition was analyzed using a LactoScan milk analyzer (Milkotronic Ltd., Nova Zagora, Bulgaria).

Statistical analysis

Data were analyzed through analysis of variance (ANOVA) procedure for 4 x 4 single Latin Square Design using General Linear Model (GLM) procedure of Statistical Analysis System (SAS 2002; version 9.0). Least-square (LS) means were separated using Tukey’s Student Range test and significant difference was accepted at p<0.05.

The model used for the analysis of data was:

Y _ijk = μ + D _i +P_j+ e_ijk

Where, Y_ijk= responsible variable; μ= Over all mean, D_i = fixed effect of i^thtreatment diet (i=1 to 4); P_j= random effect of j^thperiod (j=1 to 4); and e_ijk= the residual error term. To evaluate the relationship between methane emission and milk yield.

Results

Feed intake

The nutrient intake of the lactating Jersey cows fed the experimental diets is presented in Table 2. Dry matter intake increased with increasing proportion of U. mutica in the diet. Likewise, cows fed UM35 and UM52 had the higher (p< 0.01) OM and CP intakes than those fed UM0 and UM17 diets. There was no significant difference in NDF (p= 0.124) and ADF (p = 0.152) intakes among treatments.

Milk yield and composition, feed efficiency and body condition scores

Table 3 shows milk yield and composition, feed efficiencies and body condition scores of dairy cows fed natural pasture hay and U. mutica hay. Daily milk yield was highest for cows fed UM52(10.7 kg milk /cow/ day) and lowest for those fed UM0 (8.36 kg milk/ cow/ day) showing the increasing trend (p< 0.01) with increasing levels of U.mutica. Cows fed 52% U. mutica (UM52) produced 2.37, 1.85 and 0.78 kg/day more milk over those fed on UM0, UM17 and UM35, respectively. However, milk fat%, protein% and % solids not fat were similar (p > 0.05) among treatments. The protein yield and feed efficiency (kg of FCM produced/ kg of DMI) for cows fed UM35 and UM52 were greater (p< 0.01) than UM0 and UM17 diets. Cows fed UM52 had the highest (p<0.01) milk lactose yield. Moreover, cows fed UM35 and UM52 showed higher (p<0.01) body condition scores compared to those fed with UM0 and UM17.

Discussion

Feed intake

Findings from this study suggest that U. mutica can be used as a basal diet to increase feed intake and milk production compared to that of natural pasture hay. In agreement to the current study, increasing the level of inclusion of improved forage (Urochloa hybrid cv. Mulato II hay) resulted in increased DM intake in sheep compared with natural grass hay (Adnew et al 2021). Also U. brizantha cv. Piata based diets compared with napier and natural grass increased DM intake and improved milk yield in dairy cows (Mutimura et al 2018). In this study, the increase in DM intake with increasing level of inclusion of U. mutica hay in the rations could be due to higher CP and ME contents of U. mutica hay than that of natural grass hay. Likewise, the inclusion of improved forage grasses in the diet affects DM intake through their influence on nutrient digestibility (Sánchez et al 2006). Moreover, Mutimura et al (2018) and Mekuriaw et al (2020) reported higher DM intake of the diets based on U. brizantha cv. piata and Urochloa hybrid cv. Mulato II in dairy cows, respectively, due to the better CP content of the grasses.

In general, feed intake is one of the most important parameters which are used to evaluate the quality of diets (Coutinho et al 2014). Hence, the increasing trend of feed intake with the increasing level of U. mutica observed in the current study suggests that 52% U. mutica can be included in the basal diet of lactating dairy cows.

Milk yield and composition, feed efficiency and body condition scores

The higher DM intakes in cows fed with 52% U. mutica resulted in higher milk yield. Cows fed with sole U. mutica hay as a basal diet had higher milk yield than cows fed with sole (0% U. mutica) natural pasture hay which might be because of the higher CP intake compared to cows fed on the other treatment diets. The lowest milk yield in cows fed on sole natural pasture, on the other hand, might be related to the lower CP intake of the diet, limiting milk production (Korir et al 2022). Greater milk production requires greater feed intakes (Kaufman et al 2018), and hence the increased milk yield observed in the current study could be related to increased DM intake with increased inclusion of improved forage in the diets (Mekuriaw et al 2020). The present finding is consistent with reports that U. brizantha cv. Piata based diets increased milk yield in lactating dairy cows compared to Napier grass (Mutimura et al 2018). The present findings indicate that improved forage such as U. mutica inclusion in the basal diets could increase the milk production of lactating dairy cows. Due to improved total DM intake and milk yield, the feed conversion efficiency, was increased by the inclusion of U. mutica as the basal diet. According to Souissi and Bouraoui (2020), there is a good relationship between milk yield and body condition score; thus, body condition score in the current study was improved at the highest inclusion level of U. mutica in the basal diet.

In the current study, the inclusion of U. mutica in the basal diet resulted in similar milk composition, except for lactose content. The similar NDF and ADF intakes among the treatment diets would have supported similar milk fat biosynthesis (West et al 1999; Oliveira et al 1999). However, the content of fat in our finding was shown to be higher than the values reported by Romero and Gonzáles (2004) for Jersey cows and by Jiménez-Ferrer et al (2015) for Jersey crossbred cows. Though the difference was not statistically significant, protein content was numerically higher when 52% U. mutica was included in the basal diets (Table 3). On the other hand, milk lactose yield was significantly higher when sole U. mutica was included in the basal diets (Table 3).

Conclusion

The high CP and relatively lower NDF contents of Urochloa mutica make it a valuable source of nutrients for feeding lactating cows in Ethiopia. Findings in this study shows that inclusion of U. mutica as a basal diet resulted in improved feed intake and milk yield in lactating Jersey cows. The fat and protein percentage of milk was not affected by the feeding of different levels of U. mutica in a diet. Hence, it was concluded that 52% of U. mutica can be included as a basal diet in lactating Jersey cows ration in southern Ethiopia thereby improving dairy production.

Acknowledgments

The authors are grateful to Wolaita Sodo dairy cattle breeding center, for allocating land for forage cultivation, experimental cows, and all the necessary materials for this experiment. We also acknowledge Ministry of education for financial support to carry out this study, and Hawassa University laboratory staff for supporting the laboratory analysis.

Conflict of interest

The authors certify that there is no conflict of interest.

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