Productive and environmental performance of dairy cows grazing Cenchrus clandestinus in small-scale dairy systems

S Carrillo-Hernández, A P Loza-Ponce, F López-González, C M Arriaga-Jordán and J Velarde-Guillén

Instituto de Ciencias Agropecuarias y Rurales (ICAR), Universidad Autónoma del Estado de México, 50090, Toluca, Estado de México, México
jvg.svlc@gmail.com

Abstract

The objective was to evaluate through on-farm participatory research the productive and environmental effect of dairy cows grazing kikuyu grass (Cenchrus clandestinus) pastures in small-scale dairy systems in Mexico. An experiment with six Brown Swiss x Holstein cows were used to evaluate daytime continuous grazing (10 h/d) of kikuyu grass pastures or pastures of two temperate grasses: perennial ryegrass (Lolium perenne) or tall fescue (Lolium arundinaceum); supplemented with 4.6 kg DM/cow/d of a farm-made concentrate. Measurements were carried out for net herbage accumulation, sward height, milk yield and composition, live weight, body condition score, and dry matter intake, including the estimation of enteric methane emissions. The assessment of pasture variables was with a split-plot design, while animal variables were analyzed with a mirror replicated 3x3 Latin Square design. There were no differences for the animal variables.; Grazing kikuyu grass pastures by dairy cows in small-scale systems is a viable option in small-scale dairy systems because its milk yield and composition are similar to temperate grasses pastures.

Keywords: dairy cows, kikuyu, methane, ryegrass, tall fescue

Introduction

Small-scale dairy systems (SSDS), whose herds comprise from 3 to 35 cows plus replacements (Fadul-Pacheco et al 2013), are key to alleviate poverty (FAO 2010). However, in the highlands of central Mexico, these systems face high feeding costs due to the feeding strategies such as cut-and-carry temperate grass pastures and the use of high amounts of commercial concentrates (Fadul-Pacheco et al 2013; Martínez-García et al 2015).

An option to reduce feeding costs is grazing (Prospero-Bernal et al 2017). However, agro-climatic conditions, management problems, and invasion of other species, predominantly kikuyu grass (Cenchrus clandestinus), lead to a partial or total loss of pastures sown to temperate grass species as perennial ryegrass (Lolium perenne) or tall fescue (Lolium arundinaceum) in a span of two or three years (Plata-Reyes et al 2018).

Kikuyu grass (Cenchrus clandestinus; KY) is a subtropical grass from Africa, which is the foraging base of dairy systems in zones of New South Wales in Australia (García et al 2014) and in Latin American countries such as Colombia (Carulla and Ortega 2016). Being a subtropical species, it stops growing at temperatures below 8ºC, it resists light frosts but does not survive low temperatures for extended periods (Garcia et al 2014). In Mexico, it is found in subtropical areas and in the highlands of central Mexico may be and alternative forage for SSDS. However, there are scarce studies on kikuyu grass for dairy production particularly in small-scale systems (Plata-Reyes et al 2018; Marín-Santana et al 2020), with no assessment of its environmental impact.

The goal of the present study was to assess in an on-farm experiment in a small-scale dairy farm the productive and environmental performance of cows grazing a kikuyu-invaded pasture in comparison with pastures of two temperate grasses.

Materials and methods

Study Area

The study was at the end of the rainy season (September 11 to October 22), following a participatory livestock research approach (Conroy 2005) through an on-farm experiment on a small-scale dairy farm in the municipality of Aculco (20° 00’-20° 17’ North and 99° 40’ - 100° 00’West), in the highlands of central Mexico; at an altitude of 2440 m, with a subhumid temperate climate, a mean annual temperature of 15 °C, summer rains and a mean annual rainfall 700 -1000 mm (Celis-Álvarez et al 2016). The experimental methods with dairy cows and with the participating farmer followed accepted research procedures by Universidad Autónoma del Estado de México.

Pastures

Three pastures of 0.86 ha were assessed: perennial ryegrass (Lolium perenne; RG), tall fescue (Lolium arundinaceum; TF) as temperate C3 grass species, and KY (Cenchrus clandestinum, established by invasion) as the subtropical C4 grass. The pastures were associated with white clover (Trifolium repens). Pastures were fertilized 20 days before the experiment began using 46 kg of nitrogen (urea). Two cows grazed on each pasture at a stocking rate of 2.33 cow/ha.

Pasture variables were net herbage accumulation (NHA) estimated according to López-González et al (2010); sward height, by means of a rising plate meter taking 20 measurements per pasture in a zig-zag pattern (weekly) and hand-plucked herbage samples simulating grazing taken over the last four days of each experimental period.

Animals

Six multiparous low yielding Brown Swiss x Holstein cows from the participating farmer’s small herd were used, with a pre-experimental yield of 8.0 kg milk/cow/day, 160 days in lactation and a mean weight of 459 kg. Cows were milked twice a day, recording yields with a clock spring balance and individual samples per cow taken at each milking. Milk fat and protein content were determined with an ultrasound milk analyzer. Live weight (LW) was recorded at the beginning of the experiment and on the last day of each experimental period using a portable electronic scale with 1000 kg capacity. At the same time, body condition score (BCS) was determined on a scale from 1 to 5 (Wildman et al 1982).

Treatments

Cows continuously grazed the pastures (from 7 to 17 hrs) with free access to water. Cows were supplemented with 4.6 kg DM/cow/day of concentrate made in the farm with 9.5 – 10% crude protein (CP): 26% ground sorghum, 26% ground maize, 26% soybean husk, 17% sugarcane bagasse with molasses, and 5% minerals; supplying half the allocation in each milking. At night, cows were kept in a tie-stall barn.

Forage and milk evaluation

Herbage and concentrate samples were dried in a drought oven at 60ºC until constant weight. Crude protein (CP) content, neutral detergent fiber (NDF), acid detergent fiber (ADF) and in vitro dry matter digestibility (IVDMD), were determined following procedures described by Celis-Alvarez et al (2016). The metabolizable energy (ME) of the forage was estimated from CSIRO (2007) equation:

ME (MJ/kg DM) = 0.172 IVDMD – 1.707

Where: IVDMD = in vitro dry matter digestibility.

Milk fat (MF) and milk protein contents were determined with an ultrasonic analyzer. Energy corrected milk was calculated as (Niu et al 2018):

ECM (kg/day) = 12.95x fat yield (kg/day) + 7.65 x protein yield (kg/day) + 0.327 x milk yield (kg/day).

Statistical analysis

Pasture variables were analyzed with a split-plot design. The model for the analysis was:

Y_ijk= µ + r_i +T_j+E_ij+p_k+Tp_jk+e

Where: response variable; general mean; r = repetitions; = effect of treatment (grass species in the pastures as main plot), = 1… 3; = residual term for main plots; = effect of the experimental periods (split plot), =1…3; = effect of the interaction between treatment and experimental period; = residual term.

Cow productive and environmental performance followed a 3x3 Latin Square design mirror repeated two times, with three 14-day experimental periods (ten days for adaptation and four days for assessment). The cows were assigned to two groups of three cows per square in function according to pre-experimental daily milk yield, parity, and days in lactation.

Treatment sequences and cows were assigned at random in the first square, while the second square was in mirror; that is to say, the sequences were repeated inversely to reduce possible residual effects (Kaps and Lamberson, 2004). The cows in the second square were similarly assigned at random to the treatment sequence (Celis-Alvarez et al 2016). The model for the analysis was:

Y_ijkl = µ+C_i +V_j(i)+ P_k+t_ι+е_ijkl

Where: µ General mean; C= effect due to the square (i = 1,2), V = Effect due to the cows in the square (j= 1,2,3), P = Effect due to the experimental period (k = 1,2,3); t = Effect due to treatment (l = 1,2,3), е = experimental error

Experiments using repeated Latin Square designs are very useful to maximise limited experimental units (Kaps and Lamberson, 2004), particularly useful in on-farm research in small-scale farms where collaborating farmers have limited resources and herds. Experiments with small number of cows and short experimental periods are well validated and accepted in the scientific literature (Miguel et al 2014; Civiero et al 2021). Short experimental periods in experiments on dairy cow feeding and nutrition research are also validated and accepted in recognised peer reviewed journals (Pérez-Ramírez et al 2012; Miguel et al 2014; 2019); so that conclusions from these experiments are valid.

Results

Pasture Variables

A positive relationship between sward height and NHA was observed between treatments (Table 1). In general, NHA was 9% higher for KY than for C3 grass. Whilst sward height of KY was 10% lower in comparison with the average height of the C3 grasses, but slightly higher (3%) than the RG height.

There were no differences between treatments (P>0.05) in the chemical composition of herbage (Table 2). However, there were differences (P<0.05) between periods as the third period exhibited higher CP, IVDMD and ME, and lower NDF.

Animal Performance

Table 3 shows results for animal performance variables. There were no differences (P>0.05) for ECM yields, milk fat or protein content.

Differences were observed (P<0.05) for LW between treatments and periods (Table 3). Cows in KY lost 2.6% of their initial LW; whereas, in C3 pastures, only 1.2% of LW was lost; such loss was more marked in the first period, with a recovery over the two following periods. However, values of live weight and body condition score should be taken only as indicators, as the short experimental periods preclude any further interpretation. On the other hand, DMI exhibited a trend (P=0.071) for a larger DM intake in the RG pasture.

Discussion

Pastures

The NHA of KY was lower in comparison with reports by Plata-Reyes et al (2018) in the same area, though in the rainy season, in which KY presented 40% more NHA compared to C3 pastures. This agrees with Neal et al (2011), in which optimally irrigated KY produced 15% more forage than RG; while in water deficit, this difference reaches 22%. The above was observed in the third period, which was the period with highest NHA, possibly from higher rainfall during such period. Sward height was within the range (5 – 8 cm) for continuous grazing (Mayne et al 2000), since below 5 cm albeit measured with a ruler, herbage DM intake is restricted. For its part, sward heigh was negatively related to its nutritional characteristics, which agrees with reports by Tuñon et al (2013), where at a lower height, the leave-stem ratio increases and so does quality.

The chemical composition of forage did not present differences between treatments possibly because the central Mexican highlands have a positive effect on KY (Marín-Santana et al 2020). This may explain why KY had a higher IVDMD than in Colombia where Carulla and Ortega (2016) reported 665 g/kg DM for regrowths at 32 and 58 days compared to 717 g/kg DM herein reported; or in Australia (631 g/kg DM) reported by García et al (2014). Nutritionally, CP content for KY was similar to reports by García et al (2014) in Australia (178 g/kg DM) and by Carulla and Ortega (2016) in Colombia (166 g/kg DM). While CP reported by Celis-Álvarez et al (2016) and Rosas-Dávila et al (2020) for RG and TF, respectively, were similar to this work’s observations.

Animal Performance

The low DMI observed (2% of LW) was the result of the high supplementation level, which reduces pH, forage digestion and decreases the pasture DMI (Bargo et al 2003). However, the supplementation level was decided by the participating farmer, which was respected as a premise of participatory rural research.

Milk yield was lower than the values observed by Clark et al (2018) in Australia, with yields of 22 – 27 kg milk/cow/day grazing KY and RG, respectively.

Tropical grasses tend to emit more CH₄ than temperate species because of a higher NDF content as well as higher lignification (Archiméde et al 2011). Albeit, in this work, C3 grasses produced 0.6% more CH ₄ as a result of a larger content of fiber (1.5%), which decreased 0.8% of IVDMD in comparison with KY. A higher percentage of fiber accounts for a larger contribution of structural carbohydrates, which are associated to longer feed retention times in rumen and changes in the pattern of volatile fatty acids, generating a larger production of CH₄ (Johnson and Johnson, 1995).

Conclusion

Results obtained in this work show that kikuyu grass pastures are a viable alternative in feeding strategies for dairy cows over the second third of lactation with no significant effect on MY or its components for small-scale dairy systems, with a nutritional value par to herbage from RG and TF temperate pastures. However, more studies are needed to assess the full potential of kikuyu for these systems in the highlands in terms of agri-environmental, economic, and productive impacts over time.

Conflict of interest

The authors declare that there was no conflict of interest regarding the material in this manuscript.

Acknowledgements

The authors express gratitude to the farmer and his family for their participation in this work, and his privacy and that of his family respected by not disclosing their names. We also thank Ms. L.E. Martínez Contreras for her support in laboratory analyses. This work received funding from Universidad Autónoma del Estado de México, through the project “Livestock feeding strategies based on quality forages for small-scale dairy production systems” funded by Program for the Strengthening of Education Quality, and a postgraduate grant for S. Carrillo-Hernández and a postdoctoral grant for J. Velarde-Guillén from the Mexican National Council for Science and Technology (CONACYT – Consejo Nacional de Ciencia y Tecnología).

References

Archimède H, Eugène M, Marie Magdeleine C, Boval M, Martin C, Morgavi D P, Lecomte P and Doreau M 2011 Comparison of methane production between C3 and C4 grasses and legumes. Animal Feed Science and Technology, 166–167: 59–4. doi: 10.1016/j.anifeedsci.2011.04.003

Bargo F, Muller L D, Kolver E S and Delahoy J E 2003 Production and digestion of supplemented dairy cows on pasture. Invited review. Journal of Dairy Science 86: 1-42. doi: 10.3168/jds.S0022-0302(03)73581-4

Caro F and Correa H J 2006 Digestibilidad posruminal aparente de la materia seca, la proteína cruda y cuatro macrominerales en el pasto kikuyo (Pennisetum clandestinus) cosechado a dos edades de rebrote. Livestock Research for Rural Development, 18: Article #143. http://www.lrrd.org/lrrd18/10/caro18143.htm

Carulla J E and Ortega E 2016 Sistemas de producción lechera en Colombia: retos y oportunidades. Archivos Latinoamericanos de Producción Animal 24(2): 83-87. https://ojs.alpa.uy/index.php/ojs_files/article/view/2526

Celis-Álvarez M D, López-González F, Martínez-García C G, Estrada-Flores J G and Arriaga-Jordán C M 2016 Oat and ryegrass silage for small-scale dairy systems in the highlands of central Mexico. Tropical Animal Health and Production 48: 1129-34. doi: 10.1007/s11250-016-1063-0

Clark C E F, Kaur R, Millapan L O, Golder H M, Thomson P C, Horadagoda A, Islam M R, Kerrisk K L and Garcia S C 2018 The effect of temperate or tropical pasture grazing state and grain-based concentrate allocation on dairy cattle production and behavior. Journal of Dairy Science101: 5454–65. doi: 10.3168/jds.2017-13388

Conroy C 2005 Participatory Livestock Research. 304. ITDG Publishing, Warwickshire, UK.

CSIRO 2007 Nutrient Requirements of Domesticated Ruminants. CSIRO Publishing, Collingwood, Victoria, Australia.

Fadul-Pacheco L, Wattiaux M A, Espinoza-Ortega A, Sánchez-Vera E and Arriaga-Jordán C M 2013 Evaluation of sustainability of small-scale dairy production systems in the highlands of Mexico during the rainy season. Agroecology and Sustainable Food Systems, 37: 882-01. doi: 10.1080/21683565.2013.775990

FAO 2010 Food and Agriculture Organization of the United Nations. Status and prospects for smallholder milk production - A global perspective, by Hemme, T. and Otte, J. FAO, Rome, Italy.

García S C, Islam M R, Clark C E F and Martin P M 2014 Kikuyu-based pasture for dairy production: a review. Crop Pasture Science 65: 787–97. doi: 10.1071/CP13414

Jiao H P, Dale A J, Carson A F, Murray S, Gordon A W and Ferris C P 2014 Effect of concentrate feed level on methane emissions from grazing dairy cows. Journal of Dairy Science 97: 7043–53. doi: 10.3168/jds.2014-7979

Kaps M and Lamberson W 2004 Change-over designs.In: M. Kaps and W. Lamberson (Eds.), Biostatistics for Animal Science, (Cromwell Press, Trowbridge, UK), 294 – 312.

López-González F, Estrada-Flores J G, Avilés-Nova F, Yong-Ángel G, Hernández-Morales P, Martínez-Loperena R, Pedraza-Beltrán P E and Castelán-Ortega O A 2010 Agronomic evaluation and chemical composition of African star grass (Cynodon plectostachyus) in the southern Region of the State of Mexico. Tropical and Subtropical Agroecosystems, 12: 1-9. http://hdl.handle.net/20.500.11799/39954

Marín-Santana M N, López-González F, Hernández-Mendo O and Arriaga-Jordán C M 2020 Kikuyu pastures associated with tall fescue grazed in autumn in small-scale dairy systems in the highlands of Mexico. Tropical Animal Health and Production 52 (4): 1919-26. doi: 10.1007/s11250-020-02216-7

Martínez-García C, Rayas-Amor A A, Anaya-Ortega J P, Martínez-Castañeda F E, Espinoza-Ortega A, Prospero-Bernal F and Arriaga-Jordán C M 2015 Performance of small-scale dairy farms in the highlands of central Mexico during the dry season under traditional feeding strategies. Tropical Animal Health and Production 47: 331-7. doi: 10.1007/s11250-014-0724-0

Mayne C S, Wright L A and Fisher G E J 2000 Grassland management under grazing and animal response. In: Hopkins A, editor. Grass: Its Production and Utilization. Chapter 10, pp. 247-291. 3rd. Edition, British Grassland Society and Blackwell Science, Oxford, UK

Miguel M F, Ribeiro-Filho H M N, de Andrade E A, Moraes-Genro M T and Delagarde R 2014 Pasture intake and milk production of dairy cows grazing annual ryegrass with or without corn silage supplementation. Animal Production Science, 54, 1810-1816. doi: 10.1071/AN14382

Miguel M F, Delagarde R and Ribeiro-Filho H M N 2019 Corn silage supplementation for dairy cows grazing annual ryegrass at two pasture allowances, Arquivo brasileiro de medicina veterinária e zootecnia 71, 1037-1046. doi: 10.1590/1678-4162-9795

Neal J S, Fulkerson W J and Hacker R B 2011 Differences in water use efficiency among annual forages used by the dairy industry under optimum and deficit irrigation. Agricultural Water Management, 98: 759–774. doi: 10.1016/j.agwat.2010.11.011

Pérez-Ramírez E, Peyraud J L and Delagarde R 2012 N-alkanes v. ytterbium/faecal index as two methods for estimating herbage intake of dairy cows fed on diets differing in the herbage, maize silage ratio and feeding level, Animal, 6, 232-244. doi: 10.1017/S1751731111001480

Plata-Reyes D A, Morales-Almaraz E, Martínez-García C G, Flores-Calvete G, López-González F, Prospero-Bernal F, Valdez-Ruiz C L, Zamora-Juárez Y G and Arriaga-Jordán C M 2018 Milk production and fatty acid profile of dairy cows grazing four grass species pastures during the rainy season in small-scale dairy systems in the highlands of Mexico. Tropical Animal Health and Production 50: 1797-05. doi: 10.1007/s11250-018-1621-8

Prospero-Bernal F, Martínez-García C G, Olea-Pérez R, López-González F and Arriaga-Jordán C M 2017 Intensive grazing and maize silage to enhance the sustainability of small-scale dairy systems in the highlands of México. Tropical Animal Health and Production 49: 1537–44. doi: 10.1007/s11250-017-1360-2

Rosas-Dávila M, Estrada-Flores J G, López-González F and Arriaga-Jordán C M 2020 Endophyte-free tall fescue pastures for small-scale dairy systems in the highlands of central Mexico. Indian Journal of Animal Science 90 (5):778–83. http://www.revista.ccba.uady.mx/urn:ISSN:1870-0462-tsaes.v23i2.3126

Taylor S H, Hulme S P, Rees M, Ripley B S, Woodward F I and Osborne C P 2010 Ecophysiological traits in C₃ and C₄ grasses: a phylogenetically controlled screening experiment. New Phytologistogist 185(3): 780–91. https://www.jstor.org/stable/25609661

Tuñon G, Kennedy E, Horan B, Hennessy D, Lopez-Villalobos N, Kemp P, Brennan A and O’Donovan M 2013 Effect of grazing severity on perennial ryegrass herbage production and sward structural characteristics throughout an entire grazing season. Grass and Forage Science, 69(1): 104–18. doi: 10.1111/gfs.12048

Velarde-Guillén J, López-González F, Estrada-Flores J G, Rayas-Amor A A, Heredia-Nava D, Vicente F, Martínez-Fernández A and Arriaga-Jordán C M 2017 Productive, economic and environmental effects of optimised feeding strategies in small-scale dairy farms in the Highlands of Mexico. Journal of . Agriculture and Environment for international Development 111(1): 225-43. doi: 10.12895/jaeid.20171.606

Wildman E E, Jones G M, Wagner P E, Boman R L, Troutt H F Jr and Lesch T N 1982 A dairy cow body condition scoring system and its relationship to selected production characteristics. Journal of Dairy Science 65: 495-01. doi: 10.3168/jds.S0022-0302(82)82223-6