Effect of maize silage and concentrates fed separately or as total mixed ration (TMR) on milk yield of Jersey cows

Habte Abebaye, Ashenafi Mengistu¹, Berhan Tamir¹, Getnet Assefa² and Fekede Feyissa²

Selale University, Ethiopia
habte.abebaye@yahoo.com
¹ College of Veterinary Medicine and Agriculture, Addis Ababa University, Ethiopia
² Ethiopian Institute of Agricultural Research (EIAR), Ethiopia

Abstract

The objective of this study was to compare the total mixed ration system (TMR) with separate feeding of roughage and concentrates (CTL). For Jersey cows (n=8) were fed green maize stover silage with 30, 40 or 50% concentrate as TMR or in the traditional way with silage and concentrates fed separately (concentrate at the rate 0.5 kg/liter of milk and maize stover silage ad libitum). The design was a double 4*4 Latin Square with periods of 24 days. For the three TMR treatments, the diets were blended daily and supplied in amounts allowing 10% refusal.

On the control diet, with concentrates and silage fed separately, milk yield was less (7.90 kg/d) than that predicted (8.67 kg/d) for a similar ratio of silage: concentrate as in the TMR system. However, as the TMR system was set to allow a 10% feed refusal it could not be ensured that the ratios of concentrate: silage consumed were exactly the same as those offered. Overall feed DM: milk ratio showed no apparent relationship with feeding system indicating that the TMR method offers no obvious nutritional benefits but is more convenient for management when mechanized feeding is practiced as in large scale “mega-farms”.

Keywords: Ethiopia, management, mega farms, stover

Introduction

The Total Mixed Ration (TMR) system is defined as a blended mixture of roughages and concentrates to supply the animal’s requirements, in a form that minimizes selection (Amado et al 2016). The TMR system is claimed to achieve maximum performance through allowing cows to consume as close to possible to their energy and protein requirements, while maintaining physical or roughage characteristics required for proper rumen function (Donna et al 2002). Previous studies have shown that TMR feeding improved the daily dry matter intake, and the crude protein digestibility as well as the digestible energy value, in cows fed on a TMR of berseem and green oat fodder (Gupta et al 2014). The same study indicated that the milk production of cows fed on the TMR was higher than that of cows fed the ingredients separately. However, there is insufficient information in Ethiopian conditions regarding the TMR feeding method and the optimum level of roughage to concentrate in such a system. Therefore, the aim of this study was to evaluate milk yield and milk composition of lactating Jersey cows fed a maize silage based TMR with different concentrate: roughage ratios, as compared with the conventional feeding method.

Materials and methods

Description of the study area

The study was conducted at Adaberga Jersey cattle research farm. The farm is a sub-unit of Holeta Agriculture Research Center and is located at 70 km West of Addis Ababa and 35 km North West of Holeta town along the Muger road. The farm was established at Adaberga wetland in 1986 for commercial milk production under government state farms starting with 400 pure Jersey pregnant heifers and two sires (foundation stock) from Denmark. It was transferred to Holeta Agricultural Research Center for a genetic improvement research program since 2007. It lies at an altitude of 2500 meters above sea levels. It is characterized by cool sub-tropical climate with the mean annual temperature and rainfall of 18⁰C and 1225mm, respectively (HARC 2010).

Animal selection and management

The eight Jersey cows had similar milk yield (8-10kg/day); with the same stage of lactation (85-105 days after parturition), similar body weight (312 ±18.7kg) and parity range (one through four). The cows were treated for internal parasites 3 weeks before the commencement of the experiment.

Silage preparation

Maize was planted for the purpose of silage preparation from the green stover. Five months after planting the cob was harvested and the green stover immediately chopped to a length of about 2cm and stored in a bunker silo. It was sprinkled with molasses layer by layer at every 15cm and compacted by tractor, then covered with plastic sheet. The feeding experiment began six weeks after ensiling.

Treatments and design

The treatment combinations (DM basis) were:

CTL: Control group (Green maize stover silage [GMSS] ad libitum) and concentrates at 0.5kg /liter of milk yield: and TMR 70:30, 60:40 and 50:50 proportions of silage:concentrate (DM basis).

A double 4*4 Latin Square Design was used. Within each square, cows were assigned randomly to the four dietary treatments. Individual feeding was practiced. The concentrate was (%) : wheat bran 69, noug cake 30 and salt 1. The cows on the control system (CTL) received the concentrate in equal portions at 5:00 am and 5:00 pm during the morning and evening milking. The maize stover silage was given ad libitum to this group of animals. The cows had free access to water and were let out for exercise 30 minutes every morning. The TMR diets were prepared daily with adjustment to allow 10% refusal. Each experimental period was 24 days (14 days of adaptation and 10 days of data collection.

Digestibility

Apparent digestibility was determined by total fecal collection for a period of 5 consecutive days at the end of each experimental period. The feces were put in plastic buckets when animals defecated. A 1% sample was taken and placed in a plastic bag. Composite samples of the daily collected feces were stored at -20⁰C until the end of the collection period, when pooled samples were thawed and a subsample taken for oven drying at 65⁰C for 72h, then ground to pass through a 1mm sieve and stored until analysis.

Chemical analysis

Samples of feed offered and refused were taken daily, bulked on a period basis and then oven dried at 65⁰C for 72h prior to analysis by the standard methods of AOAC (1990). NDF and ADF were determined according to Van Soest and Robertson (1985).

Milk yield and composition

Hand milking was carried out twice a day at 5 a.m. and 5 p.m. Milk samples from morning and evening were taken for three consecutive days in each milking period. An auto-scan milk analyzer (milko-scan 133R) was used to determine fat, protein, total solids and lactose.

Data management and analysis

Data were analyzed by Statistical Software (SAS 2004). The model for the design was

Y_ijk= µ + S_i+ C _j + P _{k +} T_m + E_ijkm,

Where, Y_ijkl is the response variable (intake, digestibility, milk yield and composition),

μ = overall mean, S_i = square effect (i = 1, 2), C_j = cow effect (parity) (j=1-4), P_k = effect of period (k=1-4), T_m= effect of treatment (diet) (m=1-4), E ijkm = experimental error.

Results

Feed ingredients

In the TMR diets the crude protein content of the complete feed increased by 25%, but the in vitro organic matter digestibility increased by only 3.2%, as the concentrate ratio increased (Table 1).

Feed intake, digestibility, milk yield and feed conversion

The increasing proportion of concentrates in the three TMR diets led to expected increases in DM intake, digestibility of crude protein and of DM, and of milk yield (Tables 2, 3 and 4; Figures 1, 2 and 3). The control feeding system with a silage;concentrate ratio of 66:34 supported the same milk production as the TMR with the ratio of 70:30. However, feed DM intake was lower on the control system, with the result that the feed:milk conversion, measured as DM intake per unit milk yield, showed no apparent trends with the feeding system (Table 4).

Figure 1. Effect of concentrate;silage ratio on DM intake in the TMR system	Figure 2. Effect of concentrate;silage ratio on crude protein digestibility in the TMR system

Figure 3. Effect of concentrate;silage ratio on milk yield in the TMR system

Discussion

On the control diet, with concentrates and silage fed separately, the yield was apparently less (7.90 kg/d) than that predicted for a similar ratio of silage: concentrate as in the TMR system (8.67 kg/d). This difference could be interpreted as reflecting the benefits of the TMR system. However, other factors have to be considered such as: on the TMR system feed was offered at 10% above the amount consumed the previous day. Thus the amount of concentrate offered in the TMR system was greater than the amount actually consumed. Despite the mixing, especially if this was done by hand, some degree of selection is likely to have occurred such that the TMR cows probably ate a diet richer in concentrates than originally planned. By contrast, on the control system consumption of concentrates was complete and any refusals would have been for the silage component. The fact that the overall feed DM to milk conversion (Table 4) showed no apparent relationship with feeding system indicates that the TMR system offers few nutritional benefits, and that its virtue lies more in its convenience, when mechanized feeding is practiced, and less than in any nutritional merit per se.

Conclusions

• When concentrates and silage fed separately, milk yield was less (7.90 kg/d) than that predicted (8.67 kg/d) for a similar ratio of silage: concentrate as in the TMR system. However, as the TMR system was set to allow a 10% feed refusal it could not be ensured that the ratios of concentrate:silage consumed were exactly the same as those offered.
  
  
• Experience indicates that the cows would make every effort to select the concentrate component than the silage, and therefore the feed residues would be composed mainly of silage.

Overall feed DM:milk conversion showed no apparent relationship with feeding system, indicating that the TMR system offers no obvious nutritional benefits but is more convenient for management when mechanized feeding is practiced as in large scale “mega-farms”

Acknowledgments

The authors are grateful to Addis Ababa University (CVMA) for funding the work and Holeta Agricultural Research Center (HARC) for allowing me to undertake the feeding experiment at Adaberga dairy farm.

References

Amado A A, Karla J S, Menandro Ty, Loresco M, Angelo M T, Myrna S G, Severino S C and Elpidio M A J 2016 Total Mixed Ration (TMR): Alternative to Conventional Feeds for Dairy Animals. Paper presented during the 19th Dairy Congress held on April 13- 15, 2016 at Negros Oriental Convention Center, Dumaguete City

AOAC 1990 Official Methods of Analysis. 15^th Edition. Arlington, Virginia, USA. pp. 12-98.

Donna M, Jose R and Larry WT 2002 Managing the total mixed ration to prevent problems in dairy cows. University of Kentucky, pp.1-4.

Gupta J J, Dey A, Bhatt B P, Chakrabarti A, Dayak S, Kumari R and Barari S K 2014 Performance of lactating crossbred cows fed on forage based total mixed ration. Livestock Research International Journal Vol (2) Issue 2 Pp. 30-32

HARC 2010 Agro- Metrology and GIS weather data of West Shewa zone for the period of 2001-2010. Holetta Agricultural Research Center (HARC), Ethiopia.

SAS 2004 Statistical Analysis System 9.1. SAS Institute. Inc., Cary, NC, USA.

Van Soest P J and Robertson J B 1985 Analysis of forage and fibrous foods. A laboratory manual for Animal Science 613. Cornell University, USA.

Received 26 November 2019; Accepted 1 January 2020; Published 1 February 2020

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