Livestock Research for Rural Development 19 (12) 2007 Guide for preparation of papers LRRD News

Citation of this paper

Evaluation of grazing regimes on milk composition of Borana and Boran-Friesian crossbred dairy cattle at Holetta research center, Ethiopia

Rehrahie Mesfin and Andnet Getachew

Ethiopia Institute of Agricultural Research (EIAR), Holetta Agricultural Research Center, P.O.Box 2003 Addis Ababa, Ethiopia
Y_takele@yahoo.com

Abstract

A study was carried out to analyze and compare percentages of milk fat, protein, lactose and total solids content of Borana and Boran-Friesian crossbred dairy cows across seasons to evaluate the grazing management of dairy cows. The study was aimed to plan proper feeding strategies across seasons in line with feed supply situations of the grazing pastureland based on recommendations drawn from results of this study.

 

Regardless of the effect of seasons, Boron cows showed higher percentage of milk fat, protein and total solids content than Friesian crossbred cows. However Friesian crossbred dairy cows showed higher content of milk lactose than local Borana cows. Highest milk fat content of Friesian crossbred dairy cows was observed in July to September and the lowest was in April to June. Highest milk fat, protein and total solids contents of local Borana cows were observed in October to December and the lowest in January to March. Friesian crossbred dairy cows had highest milk protein in July to September and the lowest in January to March. However milk lactose content of Borana and Boran-Friesian crossbred dairy cows did not  differ across seasons. Milk total solids content of Boran-Friesian crossbred dairy cows was highest in July to September and the lowest in January to March. Milk fat and protein contents of Boran and Boran-Friesian crossbred dairy cows were higher in July to September and October to December as compared to rest of the seasons. Similarly total solids content of Boran cows was higher in July to September and October to December as compared to rest of the seasons.

 

Feeding management should be planned and implemented to Borana and Boran-Friesian crossbred dairy cows across seasons independently. There is a need to properly feed dairy cows particularly in seasons when shortage of grazing land affects milk composition.

Key words: Fat, lactose, season, total solids


Introduction

Cow breeds indigenous to Ethiopia are characterized by:  high values for milk composition, low milk yield (hardly exceeds 600 liters in a short lactation of less than 200 days), a long time to get the first calf (ranging from 3.5 to 4 years) with long calving interval (Kiwuwa et al 1983; Beyene 1992; Sendros et al 2003).

 

To improve milk productivity of local cows, crossbreeding with exotic breed was proved to be promising for the highlands and mid altitude zones of Ethiopia (McDowell 1985a; McDowell 1985b; Mohammed et al 1987; Sendros et al 1987a; Sendros et al 1987b; Beyene 1992; and Sendros et al 2003).  To undertake continued crossbreeding activities, the Holetta Agricultural Research uses local Borana cows and exotic Friesian semen to produce Boran-Friesian crossbred dairy cattle, which have been reported to be promising for the highlands of Ethiopia (Beyene 1992; Mengistu et al 2000; Solomon 1996; Zerbini et al 1993).

 

The nutritional value of milk is high. It contains fat, protein, lactose, minerals, vitamins and enzymes mixed in water. Milk constituents therefore are very important to dairy product manufacturers. They influence the yield of butter and cheese. Besides milk yield, composition of milk has become more important due to the rise in price of butter and cheese in recent years in Ethiopia. Thus, milk composition is becoming a crucial factor in determining profitability of dairy farming.

 

The composition of milk varies considerably with breed type, stage of lactation, feed, season of the year, and many other factors (Charles 1998).  The cow’s diet is the ultimate source of most of the material used in milk synthesis. The conditions of feeding and the rations fed to the cow influences the percent and yield of milk composition (Robinson 1997).  The nutritional status of cows in relation to optimization of milk constituents can be adjusted through proper grazing and feeding management (Robinson 1997). This study therefore is aimed at investigating the grazing status of Borana and Boran-Friesian crossbred dairy cattle breeds through analysis of milk composition across seasons. Evaluation of the grazing situation is a goal to plan improved feeding strategy in line with the grazing regimes of the pastureland so as to maximize productivity of dairy cattle. This will help to foster proper feeding recommendations when crossbred dairy cattle are released to smallholder farmers.

 

Materials and methods 

Location and climate of the study area

 

The study was carried out at Holetta Agricultural Research Center (HARC). Holetta is one of typical highland areas of Ethiopia, which is literally conducive for smallholder dairying. It is located at 45km west of the capital City, Addis Ababa with an altitude of 2400 meters above sea level. It is situated at 90 3’N latitude and 380 38’ E longitudes. The area receives an annual rainfall of 1100 mm with an average maximum temperature of 21.3oC (18.6-24oC). 

Experimental cows

Two breeds of cows were used for the study. Borana cows are local to Ethiopia. They are used as dam breeds for the crossbreeding activities. They are bred with exotic Friesian sire (semen) to produce Boran-Friesian crossbred cattle. The second breed type is crossbred of Boran-Friesian dairy cows, the one recommended promising to release to the smallholder farmers.

 

Feeding management of the dairy cows

 

The feeding system of dairy cows at Holetta Agricultural research centre is roughage based and supplemented with concentrate feeds (mixture of 31% wheat bran, 33% wheat middlings, 35% noug cake and 1% common salt. The supplementation status of concentrate feeds is similar across the entire year. However, the supply of roughage from the grazing pastureland varies with seasons.

 

Among the four seasons, dairy cows were allowed to graze on natural pasture of the dairy farm for three consecutive seasons (October to December, January to March, and April to June). They graze for approximately 8:00 hrs in a day from 7:00 hours to 15 hours. However, during the heavy rainy season (July to September), the grazing pastureland is protected from grazing for purpose of producing hay to be used as roughage feed for the entire year. During this season, dairy cows are restricted to little grazing on back yard of the research campus. They are supplemented with ample cut and carry of green grass and little conserved hay. For the whole year, milking cows are supplemented with mixture of local concentrate feeds during milking.

 

The pasture hay is harvested starting from October to November. After harvesting cows are released to graze and they consume ample left over from the harvested pastureland. Through time, particularly during April to June, the left over gets diminished.

 

Measurements, sampling and chemical analysis

 

Data of 3 years (2003-2005) were collected and analyzed for fat, protein, lactose and total solids contents of milk from Boran and Boran-Friesian crossbred dairy cows. Milk Samples from morning and evening milkings were collected and make a composite. Laboratory analysis for milk fat, protein lactose and total solids was investigated based on the scientific procedures of the Lacto scope machine. 

Method of statistical analysis

Data close to 13162 were used for analysis. Fat, protein, lactose and total solids contents of milk were subjected to Analysis of Variance using General Linear Model (GLM) procedures of SAS (Statistical Analysis System Institute release 6.12, 1999). 

 

Since the study was based on laboratory analysis, a higher precision is expected in procedures of measurements and laboratory analysis. Thus the probability level used to compare variations between milk compositions of breeds of cows across seasons was at 1%.

The statistical model used was:

Yijk=µ + ti + e i

Where:

Yijk is the dependent variable (milk fat, protein, lactose and total solids)

µ is overall mean

ri is effect of treatment

ei random variation.

 

Results 

The investigation made to compare milk compositions between the two breeds showed that, there are significant (P<0.01) differences on all milk compositions between Borana and Friesian crossbred dairy cows (Table 1). i.e., Boran cows have shown significantly (P<0.01) higher percentage of milk fat, protein and total solids than Friesian crossbred cows. Whereas Friesian crossbred dairy cows have shown significantly (P<0.01) higher content of milk lactose than Borana cows.


Table1.  Milk fat, protein, lactose and total solids percent of Boran and Boran-Friesian

 crossbred dairy cows

Milk composition, %

LS-Means and SE, %

Boran-Friesian cross

Borana cows

Milk fat

5.48 ± 0.02a

6.01  ± 0.05b

Milk protein

3.80  ± 0.03a

4.05 ± 0.05b

Milk lactose

4.18  ± 0.05a

4.00   ± 0.05b

Milk total solids

15.32 ± 0.03a

16.02  ± 0.05b

ab Least square means with different superscripts within  row differ at P<0.01


The analysis made to examine situation of milk composition of Boran-Friesian crossbred dairy cows across different seasons showed that, significantly (P<0.01) highest milk fat content was observed during July to September and the lowest was recorded during April to June Table 2).


Table 2.  Milk fat percent of Boran-Friesian crossbred dairy cows across seasons

Season

Ls-Means and SE, %

January to March

5.47 ± 0.05a

April to June

5.39 ±  0.04a

July to September

5.60 ±  0.05 b

October to December

5.46 ± 0.05a

abLeast square means with different superscripts within column differ at P<0.01


Concerning milk compositions of Borana cows across different seasons, significantly (P<0.01) highest milk fat content was observed in October to December and the lowest was recorded in January to March (Table 3).


Table 3.  Milk fat percent of Boran cows across seasons

Season

Ls-Means and SE, %

January to March

5.65 ± 0.13 a

April to June

5.69 ± 0.13 a

July to September

6.29  ± 0.13 b

October to December

6.51  ± 0.13bc

abc Least square means with different superscripts within column differ at P<0.01


Regarding to percentage of milk protein across different seasons, Friesian crossbred dairy cows have shown the highest protein content in July to September and the lowest was in January to March. Milk protein content of Friesian crossbred dairy cows in April to June, July to September and October to December were significantly (P<0.01) higher than January to March (Table 4).


Table 4.  Milk protein percent of Boran-Friesian crossbred dairy cows across seasons

Season

Ls-Means and SE, %

January to March

3.63 ± 0.052 a

April to June

3.84 ± 0.048b

July to September

3.86 ± 0.048b

October to December

3.85 ± 0.048cb

abcLeast square means with different superscripts within column are differ P<0.01


In the case of Borana cows (Table 5), they have recorded significantly (P<0.01) highest milk protein content in October to December and the lowest was in January to March.  


Table 5.  Milk protein percent of Borana cows across seasons

Season

Ls-Means and SE, %

January to March

3.88 ± 0.04 a

April to June

3.96 ± 0.04 a

July to September

4.14 ± 0.04 b

October to December

4.25 ± 0.04 bc

abcLeast square means with different superscripts within column differ at P<0.01


As indicated in Table 6, the analysis made to compare milk lactose content of Borana-Friesian crossbred dairy cows across seasons showed that, lactose percent of milk in April to June appeared significantly (P<0.01) higher than the rest of the seasons.


Table 6.  Milk lactose percent of Boran-Friesian crossbred dairy cows across seasons

Season

Ls-Means and SE, %

January to March

4.16 ± 0.015 a

April to June

4.22 ± 0.014 b

July to September

4.16 ± 0.014 cd

October to December

4.16 ± 0.014 ac

abcdLeast square means with different superscripts within column differ at P<0.01


As indicated in Table 7, milk lactose content of Borana cows in January to March was the highest and the lowest was in October to December. Significantly (P<0.01) highest milk lactose appeared in January to March.


Table 7.  Milk lactose percent of Boran cows across seasons

Season

Ls-Means and SE, %

January to March

4.07 ± 0.04 a

April to June

4.01 ± 0.04 ab

July to September

4.03 ± 0.04 a

October to December

3.86 ± 0.04 b

abLeast square means with different superscripts within column are differ at P<0.01


As shown in Table 8, milk total solids content of Boran-Friesian crossbred dairy cows was significantly (P<0.01) highest in July to September and October to December and the lowest was in January to March.


Table 8.  Milk total solids percent of Boran-Friesian crossbred dairy cows across seasons

Season

Ls-Means and SE, %

January to March

15.10  ± 0.08 a

April to June

15.28  ± 0.07 ac

July to September

15.52  ± 0.07cd

October to December

15.35  ± 0.07abd

abcdLeast square means with different superscripts within columns differ at P<0.01


As indicated in Table 9, milk total solids of Borana cows were significantly (P<0.01) highest in October to December and the lowest was in January to March.


Table 9.  Milk total solids percent of Boran cows across seasons

Season

Ls-Means and SE, %

January to March

15.47  ± 0.19 a

April to June

15.59  ± 0.19 a

July to September

16.48 ± 0.19 b

October to December

16.66 ± 0.19 b c

abcLeast square means with different superscripts within column differ at P<0.01


Discussion

The result of this study showed that the different breeds (Boran and crossbred Boran-Friesian) have showed significant variation in milk constituents (Table 1). Boran cows have showed higher percentage of milk fat, protein and total solids content than Friesian crossbred cows. These findings have similarity with results of Gonthier et al (2005) that reported the type of breed affects milk composition. Total solids of milk produced by Holstein cows averaged 12.4% versus 14.6% for Jerseys. Holsteins produced less milk fat (3.7% vs. 5.1%), solids-not-fat (8.7% vs. 9.5%), and protein (3.1% vs. 3.7%). Holstein cows had 12.4%, 3.7%, 8.7%, 3.1%, 4.9% total solids, fat, solid-not-fat, protein and lactose respectively. Where as Jersey cows had 6%, 5.1%, 9.5%, 3.7% and 5% total solids, fat, solid-not-fat, protein and lactose respectively. Similarly Charles (1998) reported that Holsteins tend to have the lowest percentage milk composition as compared to Jersey, Ayrshire and Guernsey breeds. 

 

The current study however showed that crossbred dairy cows have higher content of milk lactose than local Boran cows (Table 4). Corruthers (1993) reported that lactose production is genetically determined. There is a difference between Jersey and Holstein cows in lactose production. The differences in lactose production have an implication to milk production. Lactose production by the udder is responsible for milk water secretion through the osmotic effects exerted by lactose. Variation in lactose production between breeds of cows has two major consequences. First a high level of lactose production relative to fat and protein results in more dilute milk and also has increased the filling rate of the udder between milking. In this regard, udders of American Holstein cattle, which produce relatively dilute milk, are full within 18 h of milking, where as New Zealand Jersey cows producing a high solids content will take up to 29 h to fill the storage capacity of the udder. Such differences are significance in the quest for reducing milking frequency without production loss, which clearly can’t be achieved in Holstein type animals. Whereas milk lactose content of Boran and Borana-Friesian crossbred dairy cows didn’t significantly (P>0.01) differ across all the seasons. This finding has similarity with the results of Gonthier et al (2005) in evaluating percentage of milk constituents by feeding micronized and extruded flaxseed to dairy cows.

 

Milk fat, protein and total solids content of Boran-Friesian crossbred dairy cows were highest in July to September and next higher in October to December and the lowest was in April to June and January to March (Table 2, 4 and 8). The highest milk fat, protein and total solids content of Boran-Friesian crossbred dairy cows recorded in July to September is due to the fact that, dairy cows are restricted to limited grazing but are supplemented with adequate amount of green grass and legumes in a cut and carry system and little hay. Such feeds are able to provide adequate amount of energy and protein to the animal.  Nutrients required for synthesis of adequate milk constituents are derived from the end products of rumen fermentation supplied by a balanced feeds, amongst which are the volatile fatty acids and microbial protein (Chenost and Sansoucy 1998). For that matter young grasses have a high feeding value and supply the cow with increased level of both ME and of CP. because leafy vegetative grasses are high quality feeds; as they mature their fiber and lignin contents increase steadily while percent protein and digestibility decrease (Harlan and Dale 1996).

 

The difference of milk composition between Borana and crossbred dairy cows across different grazing regimes may be due to the influences of breed differences in feed conversion efficiency to specific feed type. The result was consistent with findings of Rodriguez et al (1997) that the Jerseys showed greater efficiency of energy conversion than Holsteins.


Conclusions

The results of this study indicate that:

 

References 

Beyene K 1992 Estimation of Additive and Non-Additive Genetic effects for Growth, Milk Yield and Reproduction Traits of Crossbred  (Bos taurus x Bos indicus) Cattle in the Wet and Dry Environments in Ethiopia. Ph.D. Dissertation. Cornell University, USA

 

Charles C 1998 Nutrition changes milk composition. Virginia Polytechnic Institute and state University. Virginia co-operative extension Virginia

 

Chenost M and Sansoucy R 1998 Nutritional characteristics of tropical feed resources. Natural and improved grassland crop residue and agricultural by products In: Speedy A and Sansoucy R (editors). Feeding dairy cows in the tropics. FAO Animal Production and Health paper # 86. Food and Agriculture Organization of the United Nations, Rome http://www.fao.org/AG/Aga/AGAP/FRG/AHPP86/Chenost.pdf

 

Corruthers 1993 In: Welch R A S, Burns D J W, Davis S R, Popay A I and Prosser CG  (editors) 1997  Milk composition, production and biotechnology in Agricultural research. # 18 AgResearch. New Zealand pastoral Agricultural Research Institute limited Hamilton, New Zealand

 

Gonthier C, Mustafa A F, Ouellet D R, Chouinard Y, Berthiaume R and Petit H V 2005 Feeding Micronized and Extruded Flaxseed to Dairy Cows. Effects on Blood Parameters and Milk Fatty Acid Composition. American dairy Science Association. Journal of dairy Science. Volume 88: 748-756 http://jds.fass.org/cgi/reprint/88/2/748

 

Harlan E W, and Dale D 1996 Controlled Grazing of Virginia's Pastures. Virginia polytechnic Institute and state University. Publication # 418-012. Virginia  http://www.ext.vt.edu/pubs/livestock/418-012/418-012.html

 

Kiwuwa G H, Trail J C M, Kurtu M Y, Getechew W, Anderson F M and Durkin J 1983 Crossbred Dairy Productivity in Arsi Region of Ethiopia. ILCA Research Report #. 11 Addis Ababa, Ethiopia  http://www.ilri.org/InfoServ/Webpub/Fulldocs/X5529e/x5529e00.htm

 

Mc Dowell R E 1985a Crossbreeding in tropical areas with emphasis in milk, health and fitness. Journal of dairy Science. Volume 68, 2418-2435 http://jds.fass.org/cgi/reprint/68/9/2418

 

Mc Dowell R E 1985b Meeting constraints to intensive dairying in the tropical areas. Cornell International Agriculture Mimeo. # 108. University of Florida Press. Florida, USA. P.459

 

Mengistu A, Zerbini E and Alemu Y 2000 Draught work efficiency of F1 crossbred dairy cows and the Ethiopian highland zebu oxen under smallholder farming context. Proceedings of the 7th annual conference of Ethiopian Society of Animal production (ESAP). Addis Ababa, Ethiopia. Pp. 134-142

 

Mohammed Y, Anders O, Asfaw T, Tegene A and Tsehay B 1987 Performance of dairy cattle research at research and dairy co-operative farms in the Arsi region of Ethiopia. In: Proceedings of 1st National Livestock Improvement Conference (NLIC). Addis Ababa, Ethiopia. Pp. 66-72

  

Robinson P H 1997 Manipulating milk Protein Percentage and Production in Lactating Dairy Cows.  Cooperative Extension Specialist, University of California Davis. CA  95616-8521

 

Rodriguez L A, Stallings C C, Herbein J H and McGilliard M L 1997 Effect of degradability of  dietary protein and fat on ruminal, blood and milk components of Jersey and Holstein cows. Journal of Dairy Science. Volume. 80:353-363 http://jds.fass.org/cgi/reprint/80/2/353.pdf

 

SAS INSTITUTE INC 1999 SAS/STATâ User's Guide. Release 6.12. SAS Institute Inc, Cary, NC, U.S.A.

 

Sendros D, Beyene K, Tesfaye K, Taye B, and Hailu G M 1987a Preliminary results of cattle crossbreeding (European x zebu) studies. I. Milk production performances of F1 cows. In: Proceedings of the 1st National Livestock Improvement Conference (NLIC). Addis Ababa, Ethiopia. Pp. 61-66

 

Sendros D, Beyene K, Tesfaye K, Taye B and Hailu G M 1987b Preliminary results of cattle crossbreeding studies. II. Growth performance of European x zebu crossbred calves. In: Proceedings of the 1st National Livestock Improvement Conference (NLIC). Addis Ababa, Ethiopia. Pp. 73-76

 

Sendros D, Neser F W C and Schoeman S J 2003 Early growth performance of Bos taurus x Bos indicus cattle crosses in Ethiopia. Estimation of individual crossbreeding effects. Animal Breeding and Genetics. Volume120, 245-257

 

Solomon M 1996 On-farm feeding management and production performance of crossbred dairy cows in Selale area (central Ethiopian highlands). MSc Thesis, AUA, Ethiopia

 

Zerbini E, Takele G, Azage T, Alemu G and Franceschini R 1993 Effect of work and diet on progesterone secretion, short luteal phase and ovulation without estrus in post-partum F1 crossbred dairy cows. Theriogenology 40: 571-584



Received 4 April 2007; Accepted 11 November 2007; Published 11 December 2007

Go to top