Previous Page Table of Contents Next Page


A note on the effect of supplementation with noug cake (Guizotia abyssinica) on the milk production of crossbred cows

D A Little, F M Anderson & J W Durkin
ILCA, P.O. Box 5689 Addis Ababa, Ethiopia


Abstract
Introduction
Materials and methods
Results and discussion
References

Abstract

In view of the importance of milk in the animal production systems of African smallholders, an experiment was conducted to evaluate the effects of feeding small quantities of noug cake (Guizotia abyssinica) to crossbred (Friesian x Zebu) cows at ILCA's Debre Berhan station in the Ethiopian highlands. Thirteen cows were randomly allocated to three treatments after stratification on the basis of stage of lactation; they were fed poor quality grass hay and molasses/urea blocks ad libitum, and experimental treatments consisted of a daily allowance of 0, 1 or 2 kg noug cake for 11 weeks.

The provision of noug increased milk yield by a mean of 35% or 1 l/d (P<0.01), with no difference in yield between the two noug treatments. Voluntary intake of hay plus block decreased linearly with increasing level of noug intake (P<0.05). It was concluded that the provision of small quantities of such oilseed cakes to lactating cows can be recommended as being economically very favourable.

Introduction

The great importance of milk in the animal production systems of African smallholders is widely recognized, and the benefit of increased milk yields gained by introducing exotic breeds, particularly the Friesian, for crossing with indigenous stock, has also been demonstrated (Schaar et al 1981). For example, a large study in Southern Ethiopia (Kiwuwa et al 1983) demonstrated that the mean milk production of local Bos indicus cattle (approx. 2.7 kg/day and 870 kg/lactation) was greatly increased in their Friesian crossbreds (approx. 6 kg/day, and 2000 kg/lactation), in conditions where concentrate feeding was practiced.

While the feeding of concentrates is impractical in many areas, significant quantities of agro-industrial by-products frequently are available to supplement poor quality grass or crop residues that form the basis of many ruminant diets in Africa. In Ethiopia such a by-product is noug cake, a widely available high protein meal, the residue after extraction of oil from the seed of Guizotia abyssinica.

The Nutrition programme at ILCA is designed to emphasize the efficient utilization of readily available resources for optimal animal production, and this paper reports an experiment in which the influence of noug cake supplementation on the milk production of cows fed grass hay was measured.

Materials and methods

Cattle and Treatments

Thirteen mature lactating crossbred cows (Friesian x Zebu) were randomly allocated to 3 treatments after stratification on the basis of stage of lactation, with an effort to ensure that average stage of lactation within each treatment was the same. The animals were maintained in individual stalls at ILCA's Debre Berhan station in the Ethiopian highlands and experimental observations made from April 21 to July 7, 1986.

Poor quality grass hay and molasses/urea blocks were fed ad libitum, and the experimental treatments consisted of a daily allowance of 0, 1 or 2 kg noug cake, with 4 cows in each of the first two treatments and 5 in the third. Hay was offered at a rate sufficient to allow for a 20% refusal. The molasses blocks, which weighed between 6 and 10.5 kg, were weighed daily and replaced when the quantity remaining was less than 2 kg. The molasses blocks were made at ILCA, with a percentage composition as follows: molasses 42, urea 10, cement 15, triple superphosphate 3, NaCl 5 and wheat bran 25.

Measurements and Sampling

The cows were weighed weekly, milked twice daily and the total daily yields recorded. Samples were obtained at each milking, and those from individual animals bulked for weekly determinations of fat and protein contents by the Gerber and formalin titration methods respectively.

Daily samples of feed offered were taken and bulked weekly, and individual feed refusals were treated likewise. Determinations of dry matter (DM) were made to allow calculations of voluntary DM intake, and the samples were subsequently analysed for N by a Kjeldahl method; OM; NDF and ADF by the methods of Goering 6 Van Soest (1979); in vitro digestibility (IVD, Tilley & Terry 1963); P (colorimetry) and Ca, Na, K, Mg, Cu. Zn, Fe & Mn (atomic absorption spectrometry). Noug cake was analysed similarly, and also for ether extract. The IVD data were used to estimate daily intakes of metabolizable energy (ME, MJ).

Data Analysis

The daily estimated ME consumption (excluding noug) and daily milk production for each cow after week one were analysed, with the fixed effect of treatment and the regressor of first week's milk production per day per cow, by the least squares procedure of Harvey (1977), using a fixed model. As the cows entered the trial at different stages of lactation, it was necessary to include the first week's daily milk production of each individual as a covariate in the model, to remove the effect of differing level of initial milk yield.

Linear contrasts of least squares estimates were computed to determine the significance of differences between treatment groups.

Results and discussion

The compositions of the hay offered and refused are given in Table 1, from which it is clear that there was no evidence of selection since these did not differ. All of the noug cake offered was consumed. Body weights, and lactation stage at the outset, are shown in Table 2. There were no significant differences between groups in any of these parameters, and no significant changes in body weight occurred during the experiment.

Table 1. Mean (± SD) composition of Hay offered and refused, and Noug Cake (DMB)


Hay Offered

Hay Refused

Noug Cake

OM (%)

91.2 ±1.77

90.6 ±0.77

89.8 ±0.71

NDF (%)

73.5 ±1.91

73.7 ±0.87

46.7 ±0.01

ADF (%)

40.6 ±1.29

43.0 ±2.66

30.6 ±0.35

N (%)

0.89 ±0.05

0.92 ±0.12

6.89 ±0.04

P (%)

0.08 ±0.03

0.09 ±0.02

1.28 ±0.01

Ca (%)

0.41 ±0.07

0.51 ±0.07

0.70

Mg (%)

0.25 ±0.04

0.25 ±0.03

0.62

Na (%)

0.13 ±0.05

0.16 ±0.03

0.10

K (%)

0.93 ±0.23

0.94 ±0.16

1.16

Cu ppm

6.4 ±1.4

5.1 ±1.0

73

Zn ppm

31.4 ±2.3

34.3 ±2.0

90

Fe ppm

346 ±85

425 ±62

169

Ether Extract (%)

-

-

2.65 ±0.13

Table 2. Mean (± SD) body weights and lactation status of groups given 0, 1 or 2 noug supplement/day

Supplement

Body wt (kg)

Day of Lactation at outset

Initial

Final

0

430 ±37

406 ±39

91 ±61

1

404 ±42

405 ±47

118 ±86

2

404 ±16

413 ±32

114 ±89

Average daily milk yields were 2.86, 3.87 and 3.96 l for the 0, 1 and 2 kg noug treatments respectively for the experimental period. The mean squares of the analysis of variance show that significant effects of treatment occurred, and that the effect of level of milk production during the first week was also significant (table 3). For this reason the statistical approach was adopted whereby individual milk yields were adjusted to a common origin, so as to remove the effects of initial differences in yield due to wide variation in the stage of lactation at the outset. The resultant figures are shown in Table 4; milk yields from the two supplemented treatments were very similar, and both significantly greater than that from the control group. Actual yields are plotted in Fig. 1, showing the marked improvement following the provision of 1 kg noug, and illustrating that no further benefit was gained from the second increment. There was no effect of treatment on the fat and protein concentrations in the milk; respective mean (± SD) percentages of fat for the 0, 1 and 2 noug treatments were 4.4 ±0.33, 4.2 ±0.59 and 4.1 ±0.29, and of protein, 2.8 ±0.36, 3.0 ±0.46 and 3.0 ±0.41.

Table 3. Mean squares from analysis of variance for effects on milk production and intake traits of cows supplemented with 0, 1 or 2 kg Noug Cake/day

Source

df

Milk yield per day

Estimated ME Intake (Hay + block) per day

Treatment

2

1.577**

22.830*

1st week


Milk yield/day

1

11.124***

0.663


Remainder

9

0.214

7.521

The mean daily intakes of hay for the 0, 1 and 2 kg noug treatments were 11.09, 11.61 and 10.83 kg DM respectively, and intakes of molasses/urea block averaged 1470,570 and 900 g/d respectively. It was estimated that the hay contained 5.99, and the molasses blocks, 5.26 MJ ME/kg. These values were used as noted above to compute intakes of ME from hay plus block against which to compare the effects of noug supplementation.

Table 4. Least squares estimates for milk production and intake traits of cows supplemented with 0, 1 or 2 kg noug cake/day


Number

Milk yield per day (kg)

Estimated ME Intake (hay-block) per day (MJ)

Overall

13

3.496

77.637

Treatment


No noug

4

2.782

79.863


1 kg noug

4

3.904

77.720


2 kg noug

5

3.801

75.329

Milk yield/day (1st week)

-

0.954

-0.209

Figure 1 Mean daily milk yield per week of cows supplemented with 0, 1 or 2 kg noug cake/day.

Table 3 shows the effect of treatment on daily estimated ME intake from hay plus block only, significant at the 10% level, whereby the intake of hay plus block decreased linearly with increasing intake of noug. The noug was estimated to contain about 10 MJ ME/kg, resulting in total estimated ME intakes for the three treatments of approximately 80, 88 and 95 MJ ME respectively, for the 0, 1 and 2 kg noug treatments. The increment of 7 MJ between the two noug treatments was not reflected in increased milk yield. There is some suggestion in the body weight data that extra tissue was being stored, since these groups respectively gained 1 and 9 kg over the experimental period, while the control group lost 24 kg (Table 2); none of these changes or differences was statistically significant, however.

In the Debre Berhan area, noug cake currently costs about 14 ¢/kg, and the market value of milk approximates 60 ¢/l. It is clear, therefore, that the extra litre of milk yielded daily bt the group supplemented with 1 kg noug, compared with the control animals, was obtained on a very economically beneficial basis, bearing in mind also the lower level of consumption of hay and molasses/urea block.

References

Goering H.K. & Van Soest P.H. 1970. Forage fibre analyses. Agriculture Handbook No. 379 (ARS, USDA).

Harvey W.R. 1977. User's guide for least-squares and maximum likelihood Computer Program. Ohio State University, Columbus.

Kiwuwa G.H., Trail J.C.M., Kurtu M.Y., Worku G., Anderson F.M. & Durkin J. 1983. Crossbred dairy cattle productivity in Arsi Region, Ethiopia. ILCA Research Report No. 11, pp 29.

Schaar J., Brannang E. and Meskel L.B. 1981. Breeding activities of Ethio-Swedish integrated rural development project: 2. Milk production of Zebu and Crossbred cattle. World Animal Review 37: 31-36.

Tilley J.M. & Terry R.A. 1963. A two-stage technique for the in vitro digestion of forage crops. Journal of the British Grassland Society 18: 104-111.


Previous Page Top of Page Next Page