Some production parameters of Blended goats in semi-arid regions of Tanzania

E.T.R. Lyatuu, S.M. Das and J.I. Mkonyi

Livestock Production Research Institute
P. O. Box 202, Mpwapwa, Tanzania

Abstract
Introduction
Materials and methods
Results and discussion
Conclusion and recommendations
Acknowledgment
References

Abstract

Data on blended goats (a three-way cross of Kamorai (55%), Boer (30%) and indigenous Tanzanian (15%) goats) were collected over a period of four years (1987-1990) at Malya and Kongwa Research Stations. These records were analysed to assess the production potential of Blended goats. Birth weights, weaning weights, weight at 72 weeks, milk yield, lactation length and butter fat content of milk were used as parameters.

At Malya the average birth weight was 2.34 kg, the average weaning weight 12.5 kg and the average weight at 72 weeks was 28.0 kg. At Kongwa the averages were 2.31, 11.6 and 27.4 kg for birth weight, weaning weight and weight at 72 weeks, respectively. Milk yields ranged from 90.0 kg to 175.5 kg during an average lactation of 236 days. Season of kidding, age at kidding and birth type all significantly (P<0.05) influenced lactation yield. Average milk butter fat content for both stations was 2.9%.

Paramètres de production chez les chèvres croisées des régions semi-arides de la Tanzanie

Résume

Des données sur des chèvres croisées (croisement trois-voies entre des caprins de race Kamorai [55%], Boer [30%] et indigène de Tanzanie [15%]) recueillies sur une période de quatre ans (1987-1990) aux stations de recherche de Malya et de Kongwa ont été analysées en vue de l'évaluation du potentiel de production de ces chèvres. Les paramètres utilisés étaient: les poids à la naissance, au sevrage et à 72 jours, la production laitière, la durée de la lactation et le taux butyreux.

A Malya, le poids à la naissance était en moyenne de 2,34 kg, le poids au sevrage de 12,5 kg et le poids à72 jours de 28,0 kg. A Kongwa, ces poids moyens étaient respectivement de 2,31, 11,6 et 27,4 kg. La production laitière variait entre 90,0 kg et 175,5 kg au cours d'une lactation moyenne de 236 jours. La saison de mise-bas, l'âge à la mise-bas et le type de naissance avaient un effet significatif (P<0,05) sur la production laitière. Le taux butyreux moyen pour les deux stations était de 2,9%.

Introduction

Raising cattle in arid and semi-arid regions has many constraints which tend to limit the supply of animal protein available to rural farmers in these areas. As goats are more 1 than cattle in feeding and other managerial aspects, they offer more potential for meat and milk production in these areas.

Increasing the meat and milk production of indigenous goats through improved management and increased feed resources is unlikely to be effective under semi-arid conditions. Therefore, genotypes should be developed which are capable of producing more meat and milk within existing environmental constraints. Although production traits are moderately heritable, it would take time to achieve substantial increases by selection within existing indigenous genotypes because the initial level of production is low. More rapid increases can be expected from crossbreeding with exotic genotypes.

Blended goats are a three-way cross between Kamorai (55%), Boer (30%) and indigenous Tanzanian goats (15%). They have phenotypically large pendulous ears and bigger bodies than indigenous goats (Des, 1989). Earlier reports on Blended goats have been presented by Das (1989,1992).

Data collected over four years (1987-1990) at Malya and Longwa Research Stations were analysed to evaluate the growth and dairy potential of Blended goats.

Materials and methods

Study sites

The two sites were the Livestock Research Centre, Malya in north-western Tanzania and the Pasture Research Centre, Kongwa, central Tanzania. They both have a semi-arid climate with savannah grassland consisting mainly of Commiphora and Combretum woody species and Eragrostis, Aristida, Bothriochloa, Hyparrhenia, Themeda and Cynodon grasses. A few paddocks at Malya are sown with Chloris gayana, while at Kongwa, paddocks are sown with Cenchrus ciliaris and some are sown with Siratro and Leucaena leucocephala.

Management of animals

Management at both locations was similar. Kids were eartagged and weighed at birth and allowed to suckle in the morning. They were reared indoors and provided with fodder and water ad libitum until weaning at 16 weeks. Does were milked once in the evening. After weaning, does were milked twice a day. Kids grazed on natural pastures from 0800 to 1500 hours in addition to receiving a daily concentrate ration (maize/rice bran arid cotton seed/sunflower seed cake) of 30 to 50 grams per kid. Female kids were bred for the first time at 72 weeks of age. Thereafter they were bred twice a year with mating seasons of 70 days each corresponding to the dry (September-November) and wet (March-May) seasons. The buck:doe ratio was 1:30. The animals were vaccinated, dipped and dewormed regularly to control disease, while clinical diseases were treated on occurrence.

Data collection and analysis

A total of 893 records on live weights at different ages and 263 milk records of Blended does from both stations were analysed in this study. Kids were weighed at birth, weaning and at 72 weeks of age. Does were weighed at mating and kidding. Pre-weaning daily milk yield was estimated by doubling the evening milk yield. Parameters analysed included weight for age (at birth, weaning and at 72 weeks of age), and lactation performance (daily milk yield, lactation milk yield, lactation length and % butter fat).

A linear model was used for analysing data on weight for age and lactation milk yield. The model included fixed effects of seasons (wet, dry), birth type (single, twin), sex (male, female), dam age (2-3, 4-5, 5-6, 6-7 and 7 years) and interaction between main effects.

Results and discussion

Growth parameters

Weights at birth, weaning and 72 weeks for Malya were 2.34 ± 0.05 kg, 12.5 ± 0.12 kg and 28.0 ± 0.73 kg, respectively. Corresponding values at Kongwa were 2.31 ± 0.08 kg, 11.6 ± 0.34 kg and 27.4 ± 0.16 kg, respectively. Birth weights of Blended kids were higher than the 2.1 kg reported for indigenous goats and Kamorai x indigenous crosses (Des and Sendalo, 1991). This was also true for weights at 72 weeks. The indigenous and Kamorai x indigenous crosses have been reported to weigh 11.7 kg and 17.5 kg, respectively (Des and Sendalo, 1991). Birth and weaning weights were also higher than those reported for Adal and for Saanen x Adal goat kids in Ethiopia (Kassahun et al, 1989) and those reported for Sudanese goats (Wilson, 1976).

Tables 1 and 2 show the effect of seasons, type of birth, sex and age of dam on the weight (kg) of Blended kids at Malya and Kongwa.

Kids born in the wet season were heavier from birth to 72 weeks old than were those born in the dry season, but mean differences were not significant (P<0.05). Das and Sendalo (1992) reported similar findings on improved goat kids at Malya. They also found that season had a significant influence (P<0.05) on both birth and weaning weights. This could be attributed to the fact that during the wet season, gravid does tend to gain weight from the lush green forages available at the farm.

Table 1. Effect of season, type of birth, sex and age of dam on weight (kg) of Blended kids at Malya.

Variable		Birth weight		Weaning weight		72-weeks weight
		n	mean	n	mean	n	mean
Season:
	wet	148	2.52	122	12.8	97	28.2
	dry	104	2.48	93	12.3	59	27.5
Average SE		0.08			0.26		1.02
Birth type:
	single	96	2.73a	81	13.5a	56	30.4a
	twin	156	2.04b	134	11 2b	90	27.1b
Average SE			0.09		0.31		1.08
Sex:
	female	115	2.11a	106	12.3	84	27.9a
	male	137	2.57b	109	12.7	62	29.5b
Average SE			0.06		0.39		1.12
Age of dam:
	2-3 yrs	67	2.15a	51	11.8	33	27.4
	4-5 yrs	110	2.22a	95	12.4	61	28.2
	6-7 yrs	41	2.47b	37	11.9	29	29.0
	> 7 yrs	34	2.41b	32	12.9	23	28.5
Average SE			0.09	0.32		1.03

ab =Means within a column (for each variable) with different superscripts differ significantly (P<0.05).

Table 2. Effect of season, type of birth, sex and age of dam on weight (kg) of Blended kids at Kongwa.

Variable		Birth weight		Weaning weight			72-weeks weight
		n	mean	n	mean		n		mean
Season:
	wet	72	2.36	56		11.8		33	26.6
	dry	55	2.28	39		11.5		25	27.9
Average SE			0.11			0.49			1.21
Birth type:
	single	51	2.64a	42		12.3a		28	29.3a
	twin	76	2.01b	53		10.6b		30	26.5b
Average SE			0.17			0.56			1.45
Sex:
	female	69	2.18a	51		9.3a		35	26.8a
	male	58	2.43b	44		12.7b		23	28.2b
Average SE			0.15			0.52			1.33
Age of dam:
	2-3 yrs	42	2.06a	31		10.7		18	26.4
	4-5 yrs	46	2.19a	38		10.4		26	28.1
	6-7 yrs	25	2.34b	16		12.2		10	28.3
	<7 yrs	14	2.42b	10		11.5		4	27.7
Average SE			0.14			0.55			1.41

ab = Means within a column (for each variable) with different superscripts differ significantly (P<0.05).

Kids born single at both sites were significantly (P>0.05) heavier than twins at birth, weaning and at 72 weeks of age. Males were significantly (P<0.05) heavier than females at birth and at 72 weeks old at Malya (Table 1). At Kongwa, males were superior in all liveweight categories (Table 2). The effects of birth type and sex on birth weight, weaning weight and mature weight agree with those reported by Chawla and Bhatnagar (1983) for Barbari and Beetal goats in India. Twins had lower birth weights than singles, probably due to their smaller size and weight in the uterus. After birth, single kids had an advantage over twins as twins had to compete for the milk from their dam. Single kids had sufficient milk for growth to weaning. Higher weights at maturity for single kids could be explained by this advantage and the positive correlation between weaning and mature weights.

Age of dam significantly (P<0.05) influenced birth weight of kids, with older does producing heavier kids than younger does.

The interaction between age of dam and type of birth for birth weights was significant (P<0.05) at Malya. Other interactions between main effects were not significant. The lack of effect of season x birth type interaction on liveweight implies that singles showed superiority irrespective of season of birth.

Differences between sites were significant (P <0.001) for weaning weight only. Similar results of the effect of location were obtained by Das and Mkonyi (1990). These differences may be attributed to differences in management, particularly in feeding subsystems. In Kongwa the availability of maize bran was erratic, but at Malya rice polish and cottonseed cake were abundant.

Dairy parameters

A total of 263 does were studied for their dairy potential, 174 at Malya and 89 at Kongwa. Average daily milk yield per doe was 0.69 kg and 0.66 kg for Malya and Kongwa respectively. Mean lactation milk yield at Malya was 170.6 (SE 4.57) kg for a mean lactation length of 245 (SE 3.11) days. At Kongwa, mean lactation milk yield was 153.4 (SE 5.42) kg for a mean lactation length of 231 (SE 4.38) days.

Daily milk yields at both sites were much lower than those reported for Beetal goats (0.9 kg) (Verma and Chawla, 1987) and Norwegian goats (1.1 kg) (Des and Sendalo, 1991).

The values for lactation milk yield were higher than those reported for Toggenburg and Anglo-Nubian crosses (85 kg and 104 kg in 143 days respectively), but lower than other dairy goats such as Saanen and Norwegian. Mean lactation milk yields of Blended goats were also lower than those reported for Jamnapari goats (202 kg in 191 days) by Sands and McDowell (1978). This could be due to the low genetic potential for milk production of the Boer and indigenous goats which crossed to form Blended goats.

Table 3 shows the effect of type of birth, season and age of dam on the dairy potential of Blended goats at Malya and Kongwa.

Does with single kids had higher lactation milk yields and longer lactation lengths at Malya. At Kongwa there was no difference in milk yield due to birth type. Does kidding in the wet season had significantly (P<0.05) higher lactation milk yields and longer lactation lengths than those kidding in the dry season. This is probably due to the availability of lush, green pastures during the wet season compared to low quality forages in the dry season.

Table 3. Effect of type of birth, season and age of dam on dairy potential of Blended goats at Malya and Kongwa.

		Lactation milk yield (kg) and length
		Malya			Kongwa
Variable		n	mean (kg)	mean (days)	n	mean (kg)	mean (days)
Type of birth:
	single	96	176.9a	251a	51	155.7	233
	twin	78	165.2b	238b	38	152.2	228
Average SE			7.34	6.25		8.44	7.61
Seasons:
	wet	99	178.6a	247a	56	158.7a	235a
	dry	75	163.1b	240b	33	146.1b	221b
Average SE			8.23	7.82		8.63	8.75
Dam age (yrs):
	2-3	45	161.8a	236a	33	144.5a	228a
	4-5	81	166.2a	241a	29	151.8b	230b
	6-7	27	172.3b	247b	15	153.9b	232b
	7 yrs	21	176.7b	246b	12	155.3b	232b
Average SE			7.68	6.27		8.77	7.21

ab = Means within a column (for each variable) with different superscripts differ significantly (P).

The effect of age of dam was significant (P<0.05) for lactation milk yields and lactation lengths at both sites, with older dams having more milk and a longer lactation period than young does. Variations in milk yield due to age of dam were similar to those reported by Steine (1975); lowest yield occured in the first lactation and highest in the fifth.

Average butter fat content was 2.9% and 2.91% for milk from goats in Malya and Kongwa respectively. This is less than that reported for Norwegian goats but higher than Norwegian x indigenous crosses (Des and Sendalo, 1991). The interactions between main effects were not significant.

Conclusion and recommendations

The results of the evaluation of some production traits of Blended goats show that Blended goats have the potential to produce both milk and meat for human consumption.

Values for lactation milk yield, daily yield and milk butter fat content of milk are lower in Blended goats than in other dairy goats in the subtropics. However, the high variation in lactation milk yield indicates that improvements could be made through breeding and selection. The higher live weights and wide variation among Blended goats indicate their potential for meat production.

Blended goats have advantages over indigenous goats for live weight and milk production. They could be used to improve the dairy and meat production by selection and crossbreeding. The introduction of Blended goats and their crossbreeds selected for high milk yields could solve the problem of insufficient milk in semi-arid areas of Tanzania. This could also improve the economic status of goat keepers throughout the country.

Improving feeding and management of practices (housing, disease control) is essential for optimum goat productivity. More studies on the quality of milk and meat produced, reproductive efficiency, disease resistance, nutrition and other managerial aspects are necessary for the establishment and characterisation of Blended goats.

Acknowledgment

The authors are grateful to the Commissioner for Research and Training for permission to present this paper. Also we would like to thank the International Foundation for Science (IFS) based in Sweden for funding this study. Last but not least we would like to give our special thanks to scientists and technicians at Malya, Kongwa and Mpwapwa for their assistance during the course of this study.

References

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