Dolichos Lablab (Lablab purpureus) in by-product based diets for lactating cows in Botswana

B. Kiflewahid and B. Mosimanyana
Animal Production Research Unit
P. Bag 0033, Gaborone, Botswana

Abstract
Introduction
Methodology
Results and discussion
Conclusion
References

Abstract

Dairy cattle feeding was based on crop stovers supplemented with Dolichos lablab (Lablab purpureus) and post-harvest residues herein after referred to as lablab. Lablab was introduced to 30 small-scale dairy farms. Average lablab dry-matter yield from 30 farms farmers (ton/ha) for 0 and 100 kg/ha single superphosphate (10.5%P) fertilizer rate were 1.23 and 1.44, respectively, but not different (P>.05). Average dry-matter yield (ton/ha) at 0, 100 and 250 kg/ha rate, on-station, were 1.41, 1.56 and 1.70, respectively, but not different (P>.05). Phosphorus fertilization did not show significant (P>.05) effect in dry-matter yield due to low seasonal rainfall and distribution patterns in the project areas (262 to 414 mm rainfall). Total quantities of lablab hay, sorghum/millet stover and sorghum chaff/husks harvested by 30 farmers was 34.1, 56.4 and 7.2 tons dry-matter, respectively.

Sorghum and millet stover dry-matter yield (ton/ha), on-farm, ranged from 0.66 to 1.74 and 0.78 to 1.00, respectively. On-station dry-matter yield (ton/ha) ranged from 1.87 to 3.46 for different sorghum stover varieties. Dry-matter yield (ton/ha) for millet, maize and cowpea stovers were 2.42, 3.04, and 1.19, respectively.

The dry-matter and nutrient contribution of leaves, stems and twines and roots to whole lablab, Tswana cowpea and ER-7 cowpea were assessed. Dry-matter contribution by leaves to whole Tswana cowpeas (57.8%) were higher than lablab (47.0%) and ER-7 cowpeas (57.8%) were higher than lablab (47.0%) and ER-7 cowpeas (48.0%). Overall the total dry-matter and nutrient contribution of leaves to whole plants was higher than stems and twines in all three crops.

Average daily milk yield/cow/day (excluding milk left for calf) for Simmental-Tswana crossbred and Tswana cows fed sorghum stover based diets supplemented with either 15% lablab (diet A) or 25% sorghum bran (Diet B) were 2.2 and 3.4; 1.4 and 1.6 kg/day, respectively. The results showed significant differences (P<.05) between breeds but not within breeds fed the different diets. Average lactation length (days) and milk yield/cow/lactation (kg) for Simmental-Tswana and Tswana cows were: 273 and 223; 760 and 338, respectively. Average birth weight for Simmental-Tswana calves (34 kg) were greater than for Tswana calves (28 kg).

Introduction

The major objective of the Small Scale Dairy Production Project was to increase milk and milk products for both subsistence and commercial use in the traditional communal farms of the Gaborone region. The project covers six localities involving 30 farmers who participate fully in dairy production research.

In order to achieve optimal production objectives, a technical and management package incorporating the approaches and strategies related to baseline survey, animal feeding, management inputs, breeding and health, fodder production and utilization, milk marketing and extension linkages were developed (APRU, 1985).

The major constraint identified was lack of adequate feed (quantity and quality) to sustain milk production particularly during the dry season. The research emphasis has been to integrate fodder crops into the farming system and establish a practical feeding programme based on planted fodder and crop residues.

This paper focuses on the nutritional characteristics and use of lablab (Lablab purpureus) in crop by-product-based diets for lactating Simmental Tswana crossbred and Tswana cows in small-scale dairy farms in Botswana.

Methodology

Feed production and conservation

The project introduced lablab to 30 participating farmers. Each farmer was provided with 20 kg of lablab seed and 100 kg of single superphosphate fertilizer (10.5% P) to plant one hectare of land. The fertilizer was applied to half of each hectare allocated for planting lablab. The seed was planted either in rows using planters or by the traditional method of broadcasting.

Three hectares of lablab was also planted at Sebele Agricultural Research Station. Superphosphate was applied at the rate of 0, 100, 250 kg/ha on each of the three 1 ha plots. Half of each plot was row planted while traditional broadcasting was used on the other half. An additional 27 ha of land were planted for bulk production and to examine the optimal stage of harvest and appropriate methods for harvesting, drying and storage.

Lablab and crop stover yields were measured using 2 metre radius circular subplots from three random locations in each farmer's plots and at Sebele Station. After measuring yield the plants were harvested, sun-dried and stored for dry season feeding. After the harvesting period the total quantities of lablab, crop stovers and post-harvest residues stored by each farmer were estimated. Dry-matter yields were also measured for several sorghum varieties, millet and maize screened on-station.

Nutritive value

Three replicate samples of fresh whole plants, leaves, stems and roots were obtained from lablab, Tswana and ER-7 cowpea plots to determine the dry-matter and nutrient contribution of each plant part. Three replicate samples of sorghum stover, millet stover, sorghum chaff, sorghum husks and sorghum bran were also submitted for laboratory analysis.

The fresh whole plants and plant parts were air-dried (60 C) prior to grinding in a Wiley Mill (1 mm screen). The dried and ground samples were saved in airtight bottles and analysed (in duplicate) for organic matter, crude protein, crude fibre, ash, Ca and P according to methods approved by AOAC (1975) and in vitro dry and organic matter digestibility according to Tilley and Terry (1963) procedures.

Feeding trial

A dry season feeding trial was carried out to determine the voluntary feed intake (VFI) and performance of Simmental-Crossbred and Tswana lactating cows fed sorghum stover supplemented with either 15% lablab (Diet A) 25% sorghum bran (Moroko) (Diet B) or 100% sorghum stover (Diet C).

Treatments A, B and C contained 7.40%, 7.01% and 5.56% crude protein; 55.56%, 63.73% and 53.90% estimated TDN, respectively. In Treatment A lablab was mixed with the stover by hand at the time of feeding; in Treatment B the sorghum bran was fed separately in split used-oil drums. The animals were also supplemented with ad libitum bonemeal-salt (1:1 w/w ratio) and vitamins A, D, E. The Treatments A and B were randomly allocated to six each of twelve farmers. Voluntary feed intake (VFI) was determined in all treatment groups by measuring the daily weight of all feed offered and weight-back over a period of seven days and for a maximum of four lactating cows per farm. Statistical analysis using the t-test (Snedecor and Cochran, 1967) was conducted on the performance data obtained from the lactating cows that completed the trial.

Dairy cattle performance

Daily milk yields were recorded by each farmer on record forms provided by the project. Each farmer was provided with two calibrated 10-litre plastic milk buckets for recording milk yield. Milk records were collected and summarised by project staff at the end of each month. All lactating in-calf and non-pregnant cows were weighed, prior to watering in the morning, during the first week (between days 1 to 5) of each month.

Calf performance

The identity of the calf and its breed, sex, dam number, initial birth weight and birth date were recorded. Initial birth weight were measured using a heavy-duty spring balance. Subsequent monthly weights were measured using an electronic mobile cattle scale with the rest of the herd.

Results and discussion

Feed production and conservation

The average dry-matter yield (ton/ha) of lablab troy by farmers and at the Sebele Research Station is shown in Table 1. Average dry-matter yield for 0 and 100 kg/ha single superphosphate fertilizer application were not significantly different (P>.05) at 1.23 (range 1.001.60) and 1.44 (range 1.09-1.94) ton/ha, respectively. The dry-matter yield at Sebele Station for 0, 100 and 250 kg/ha single superphosphate application were 1.41, 1.56 and 1.70 ton/ha, respectively, but were also not significantly different (P>.05). The results also showed no significant differences (P>.05) in dry-matter yield between farmers' fields and Sebele Station. Phosphorus fertilizer application resulted in no change in plant constituents.

Random soil samples taken for soil nutrient analysis from farmers' fields and Sebele Station were generally acidic in all locations, with pH 4.50-4.90 at Sebele Station. There was a wide variation in soil content for farmers' fields (3.40-13.85 ppm) and at Sebele station (4.91-15.82 ppm). Several findings have shown that phosphorous fertilization increases dry-matter yield, crude protein content by stimulating nodulation, and dry-matter digestibility of fodder legumes (Haque et al, 1986). The result from this fertilizer trial could not be conclusive due to the low seasonal rainfall experienced in the project area (262 to 414 mm range). The low yields and lack of response to superphosphate application could largely be attributed to this. Dry-matter yields of lablab did not appear to relate closely to variations in rainfall patterns in the project area. For example at Oodi (414 mm, 1.32 ton/ha DM) yields were lower than Kopong (262 mm, 1.60 ton/ha DM). These observations may also be attributed to planting time, rainfall distribution and differences in soil characteristics.

Table 1. Dry matter (ton/ha) of lablab hay (Lablab purpureus) from project farms and Sebele Research Station as influenced by fertilizer application research rate².

Location and number of farmers	Fertilizer	application rate	(kg/ha)
	0	100	250
Oodi (4)	1.32	1.37	-
Bokaa (8)	1.00	1.09	-
Kopong (2)	1.60	1.94	-
Mmopane (4)	1.08	1.20	-
Gabane (4)	1.12	1.64	-
Kumakwane (8)	1.24	1.42	-
Mean	1.23a	1.44a	-
Sebele mean	1.41a	1.56a	1.70a

1. Data from three replicate yield measurements from each of 30 project farmers' plots.

2. Single superphosphate fertilizer (10.5%P).

Means in the same row and column with same superscript (a) are not significantly different (P>.05).

The average dry-matter yield of crop stovers on project farms and at Sebele Station is shown in Table 2. The yields of sorghum and millet stovers by farmers varied from 0.61 to 1.74 and 0.78 to 1.00 ton/ha of dry matter, respectively. Despite similar rainfall patterns sorghum and millet stover yields from the Sebele Station crop screening trial plots were higher than those from the farmers' fields.

Table 2. Dry-matter yield (ton/ha) of crop stovers harvested by project farmers¹ and Sebele Research Station².

Location and number of farmers	Type of feed
	Sorghum stover	Millet stover	Maize stover	Cowpea (Tswana)	Cowpea (FR7)
Oodi (3)	1.45	1.00	-	-	-
Bokaa (3)	0.61	0.82	-	-	-
Mmopane (2)	0.66	0.78	-	-	-
Gabane (1)	1.35	-	-	-	-
Kumakwane (2)	1.74	-	1.22	-	-
	3.44(a)	2.42(e)	3.04(f)	1.19	1.32
Sebele	1.87(b)	-	-	-	-
Station	3.46(c)	-	-	-	-
	3.46(d)	-	-	-	-

1. Data from three replicate yield measurements from each farmer's plot.

2. Sorghum, millet, maize and cowpea stover yields from Sebele agronomy and Botswana Agricultural College screening trials.

(a) Segaolane.	(d) Marupantsi.
(b) Town.	(e) Serere 6A.
(c) 65 D.	(f) Kalahari Early Pearl (KEP).

Maize stover yields of 3.04 ton/ha were achieved on station but farmers' maize generally failed. The higher on station yields are largely attributed to the effects of time of planting and use of fertilizer. Farmers harvested sorghum and millet stovers only.

Although farmers intercropped cowpeas with either sorghum or millets the yields were not measured. However, the dry-matter yields (ton/ha) for pure stands of Tswana cowpeas and as ER.7 cowpeas at Sebele station were 1.19 and 1.32, respectively.

At the end of the harvest season all farmers stored lablab hay, crop stovers and sorghum chaff/husks for dry season feeding. As shown in Table 3, there was a wide range in total quantities of feed conserved. Whereas all farmers harvested lablab from their 1-ha plots, harvesting of crop stovers primarily depended on the family labour available and the size of their planted field. Average quantities of lablab hay, sorghum/millet stover and sorghum chaff or husks harvested by farmers ranged from 1.04 to 1.65, 0.65 to 3.42 and 0.14 to 0.33 ton dry matter, respectively.

The total quantities of lablab hay, sorghum/millet stover and sorghum chaff/husks harvested by all the thirty participating farmers was 34.09, 56.44 and 7.17 tons dry matter, respectively. In addition a few farmers harvested small quantities of cowpea stover.

Table 3. Quantities of crop residue and lablab hay (ton DM) conserved by project farmers (1985-86).

Location and number of farmers		Lablab hay	Sorghum/millet stover	Sorghum chaff/husks (Moko)
Oodi	(4)	5.39	13.68	0.96
mean		1.35	3.42	0.24
Bokaa	(8)	8.30	19.42	1.59
mean		1.04	2.43	0.20
Kopong	(2)	3.29	4.23	0.29
mean		1.65	2.12	0.14
Mmopane	(4)	4.55	2.60	0.99
mean		1.14	0.65	0.25
Gabane	(4)	4.24	6.56	0.72
mean		1.06	1.64	0.18
Kumakwane	(8)	8.32	9.92	2.62
mean		1.04	1.24	0.33
Total	(30)	34.09	56.41	7.17
Overall mean		1.14	1.88	0.24

The major constraint observed during harvesting and conservation of lablab was the duration of time required to dry the stems. Lablab leaves dry and shatter within three days while it takes up to six weeks for the stems to dry completely. In view of this various methods of drying and storage using tripods, stocking on the ground and combining three rows into one row were tried at Sebele Station. Methods of drying had no effect on duration of drying time but the crop was baled more efficiently from stocks and tripods with minimum dry-matter loss due to leaf shattering, mouldiness or termite damage.

Nutritive value

Lablab and crop stover samples were submitted for laboratory nutritive value analysis (Table 4). There was a wide variation in dry-matter percent within the sorghum and millet stovers harvested by different farmers. The variation in dry-matter percent was attributed to the stage of maturity of the crops when harvested. Conversely there was much less variation in dry-matter percent of lablab harvested at the flowering stage.

Table 4. Percent dry matter of crop stovers and lablab conserved by project farmers (1985-86).

Location	Sorghum stover	Millet stover	Maize stover	Cowpea stover	Dolichos lablab
Oodi	40.4	39.1	-	-	21.6
Bokaa	32.4	33.3	-	-	22.3
Kopong	-	-	-	-	24.7
Mmopane	35.7	30.0	-	-	24.9
Gabane	35.3	-	-	24.8	27.5
Kumakwane	40.5	-	53.8	20.4	23.9

The average nutrient compositions and in vitro dry and organic matter digestibility of lablab, crop stovers and post-harvest residues are shown in Table 5. The mean crude protein and crude fibre percentage of lablab, cowpea stover, sorghum stover and millet stover were: 16.44 and 27.67; 15.67 and 21.08; 6.37 and 32.52; 5.75 and 35.94; respectively. On average the lablab and cowpea stover contained 2.5 times more crude protein than the sorghum and millet stovers. As shown in Table 5 the dry-matter and organic matter digestibilities of lablab and cowpea stover were higher than those of sorghum and millet stover. The higher digestibility coefficients are attributed to the higher crude protein and lower crude fibre content in lablab and cowpea stover than in the sorghum and millet stovers.

In view of these nutritional findings, diets for lactating and in calf dairy cows in the project areas were based on combinations of home grown lablab, cowpea, sorghum and millet stovers and post-harvest residues such as sorghum bran (Moko) and sorghum husks/chaff.

Table 5. Nutrient composition and in vitro dry-matter and organic matter digestibility of crop stovers and fodder legumes conserved by project farmers (1985/86).

Per cent composition of dry matter							DMD	OM
Feed	Organic matter	Crude protein	Crude fibre	Ash	Ca	P
Lablab	90.8	16.4	27.7	9.2	0.3	0.2	59.9	57.1
Cowpea stover	89.1	15.7	21.1	10.9	0.2	0.2	74.1	70.1
Sorghum stover	91.6	6.4	32.5	8.4	0.4	0.1	54.9	9.8
Millet stover	89.5	5.8	35.9	10.5	0.4	0.1	52.2	45.1
Sorghum chaff	93.6	5.5	36.6	6.4	0.5	0.1	55.5	49.7
Sorghum husks	90.0	7.2	26.8	10.0	0.3	0.2	54.4	47.2
Sorghum bran	97.3	11.5	3.2	2.7	0.4	0.3	56.9	48.3

(1) Mean data from three replicate samples per farmer's field.

The fresh and dry-matter contribution of leaves, stems and twines and roots to whole lablab, Tswana cowpea and ER-7 cowpea plants is shown in Table 6. The percentage dry-matter contribution to whole plants by leaves of Tswana cowpeas (57.8%) were higher than lablab (47.0%) and ER-7 cowpeas (48.5%). Stems and twines for lablab (46.6%) and ER. 7 cowpeas (40.5%) were higher than Tswana cowpeas (31.1%). Overall, on both fresh and dry-matter basis the contribution of leaves to whole plant was higher than stems and twines in all three crops. Roots constituted a very small proportion of the total dry-matter in the plants studied.

Table 6. Fresh and dry-matter percent contribution by plant parts to whole lablab and cowpea residue¹.

	Dolichos	Lablab	Cowpea	(Tswana)	Cowpea	(ER-7)
Plant parts	Fresh	Dry	Fresh	Dry	Fresh	Dry
Leaves	53.3	47.0	62.9	57.8	57.4	48.0
Stems and twines	42.8	46.6	30.0	31.1	35.0	40.5
Roots	3.9	6.4	7.1	11.1	7.6	11.5
Whole plant	100.0	100.0	100.0	100.0	100.0	100.0

1. Mean data from three replicate samples of whole plants divided into plant parts.

The nutrient composition of fresh lablab, Tswana cowpeas and ER-7 cowpeas is shown in Table 7. There was a marked difference in crude protein and crude fibre percentages between leaves, stems and twines and roots in all plants. The crude protein and crude fibre percentage of fresh leaves of lablab, Tswana cowpeas and ER-7 cowpea were: 19.37 and 19.32; 21.24 and 13; 22.86 and 11.52, respectively. The average crude protein content of leaves was not greatly different. Stems and twines were generally lower in crude protein and higher in crude fibre than the leaves. However, as shown in Table 7, there was less difference in the crude protein content of leaves and stems/twines in the cowpea plants than in the lablab plants.

Table 7. Nutritient composition of lablab and cowpea residue whole plant and parts 1.

		Composition of dry matter (%)
		Dry matter (%)	Organic matter	Crude protein	Crude Fibre	Ash	Ca	P
Lablab
	Leaves	21.6	87.8	19.4	19.3	12.2	0.7	0.1
	Stems and twines	26.7	92.7	11.5	37.1	7.3	1.1	0.1
	Roots	41.1	93.9	6.0	45.4	6.1	1.0	0.1
	Whole	25.3	91.5	16.6	30.3	8.5	0.6	0.2
Cowpea (Tswana)
	Leaves	16.9	84.9	21.2	13.1	15.1	0.5	0.3
	Stems and twines	19.1	90.3	21.0	18.5	9.7	0.3	0.3
	Roots	28.8	93.0	12.7	18.5	7.0	0.2	0.2
	Whole	21.2	85.4	21.3	16.8	14.6	0.3	0.2
Cowpea (ER-7)
	Leaves	19.1	85.0	22.9	11.5	15.0	0.5	0.3
	Stems and twines	26.5	92.5	19.4	21.3	7.5	0.2	0.3
	Roots	34.7	94.7	11.1	23.5	5.3	0.3	0.2
	Whole	25.4	88.5	19.2	18.3	11.5	0.4	0.3

1. Data from three replicate samples of whole plants from Sebele Research Station.

Summaries of the mean dry organic matter in vitro digestibility coefficients of fresh lablab, Tswana cowpea, ER-7 cowpea whole plant and plant parts are given in Table 8. Digestibilities of the dry matter and organic matter in lablab leaves were higher (67.85, 62.22) than in stems and twines (56.97, 50.78), but in the cowpeas the digestibilities of the stems and twines were higher than in the leaves. Between the plants the digestibilities of dry matter and organic matter were higher in Tswana and ER-7 cowpeas (73.57% and 73.85%) than in lablab (67.85%).

Table 8. In vitro dry-matter and organic matter digestibility (DMD and DOM) of lablab and cowpea residue whole plant and parts¹ .

Lablab		DMD (%)	DOM (%)
	Leaves	67.8	62.2
	Stems and twines	57.0	50.8
	Roots	46.9	43.8
	Whole	60.8	55.1
Cowpea (Tswana)
	Leaves	73.6	71.5
	Stems and twines	84.2	82.7
	Roots	74.3	73.3
	Whole	72.3	71.7
Cowpea (ER-7)
	Leaves	73.8	73.1
	Stems and twines	77.5	77.0
	Roots	76.7	76.2
	Whole	71.4	69.8

¹. Means represent data from three replicate samples.

Feeding trial (dry season)

The average chemical composition and voluntary feed intake by farmers' lactating cows fed diets of 85% sorghum stover + 15% lablab (Treatment A), 75% sorghum stover + 25% sorghum bran (Treatment B) and 100% sorghum stover (Treatment C) were presented previously (Mosimanyana and Kiflewahid, 1987).

Chemical analysis of the lablab and sorghum bran-supplemented diets indicated that the crude protein percentages were 7.40 and 7.01, respectively and higher than the sorghum stover only diet which contained 5.56% crude protein. The crude protein content of sorghum stover was lower than the minimum 7.0% required for maintenance. In Treatments A and B the crude protein contribution to the diet by lablab and sorghum bran was 37.7% and 39.4%, respectively. In terms of the crude protein contribution to the sorghum stover-based diet 15% lablab was equivalent to 25% sorghum bran.

Mean daily dry-matter intake (DMI) during the trial period for the three treatments was lower for the lablab diet (8.27 kg DM/day) than for the Sorghum bran (10.21 kg DM/day) and the sorghum stover only (8.96 kg DM/day) diets.

Dairy cattle performance

The lactation data of the Simmental-Tswana crossbred and Tswana cows fed diets of sorghum stover supplemented with 15% lablab or 25% sorghum bran, are summarised in Table 9. Complete lactation data of the cows fed the sorghum stover only diet could not be obtained since farmers started to supplement their cows with either lablab or sorghum bran prior to the end of the lactation period.

The average lactation length of Simmental-Tswana crossbred and Tswana cows fed the 15% lablab and 25% sorghum bran diets were 270 and 240, 276 and 206 days, respectively. Lactations for Simmental-Tswana cows were longer (P<0.5) than for Tswana cows. There were no significant differences (P>.05) in lactation length within breeds fed different diets.

Average daily milk yield/cow for Simmental-Tswana crossbred and Tswana cows fed the 15% lablab and 25% sorghum bran diets were 2.2 and 3.4, 1.4 and 1.6 kg/day, respectively. Within breeds the milk yields were higher for cows fed the sorghum bran but not significantly (P<0.05). There were wide variations in daily milk yield within breeds and between treatments. These observations could be attributed to the variation in genetic potential of the individual Simmental-Tswana crossbreeds and Tswana cows owned by the different farmers (APRU, 1986; DPR, 1987).

Table 9. Milk yield¹ of Simmental-Tswana (SX)² and Tswana (TS) cows fed sorghum stover supplemented with lablab or sorghum bran³ (1985-86).

	15% Dolichos Lablab + 25% sorghum bran
	85% sorghum stover		75% sorghum stover
	SX	TS	SX	TS
Number of lactating cows	5	12	5	12
Average lactation length (days)	270a	240b	270a	206b
Total milk yield/herd (kg)	2941.3	4080.6	4655	4040.1
Average lactation yield/cow (kg)	588.3a	340b	931a	336.6b
Average milk yield/cow/day (kg)	2.2a	1.4b	3.4a	1.6b

¹. Excluding milk left over for calf.

². Milk recording period 1st lactation (Nov. '85-Sept.' 86).

³. Plus ad lib bonemeal-salt (1:1 W/W ratio) and vitamin A, D, E. Means in the same row with different superscripts (a, b) were significantly different (P<0.05).

The average milk yield/cow/lactation for Simmental Tswana cows fed the 15% lablab and 25% sorghum bran diets were 583.3 kg and 931.0 kg, respectively. These values were not significantly different (P>.05) due to the large variation in milk yield within the Simmental crossbreeds. The milk yields of the Tswana cows for the two treatments (340 kg, 15% lablab diet and 336.7 kg for 25% sorghum diet) were also not significantly different (P>0.05).

At the end of the lactation period total milk produced by ten Simmental-Tswana and twenty four Tswana cows was 15,717.4 kg of which 7596.7 kg was from the ten crossbred cows and 8,120.7 kg from the 24 Tswana cows. On average under similar feeding and management systems each Simmental-Tswana crossbred cow produced 2.25 times more milk than Tswana cows. These observations are comparable to data obtained from similar trials on-station (APRU, 1986, DPR '86-87).

Average seasonal liveweight change patterns for both Simmental-Tswana crossbred and Tswana cows were similar. Despite dry season weight loss average initial liveweight for Simmental-Tswana (422 kg) and Tswana cows (379 kg) were not greatly different than weights for the same Simmental-Tswana (417 kg) and Tswana cows (365 kg) recorded after twelve months.

Calf performance

The average liveweight changes of all calves are summarised in Table 10. Birth weights of Simmental Tswana calves (34 kg) were higher than Tswana calves (28 kg). Growth patterns of both breeds were similar. In terms of management all calves had access to their dams until the end of the lactation period and weaning coincided with the end of the lactation. On-station trial results have indicated that suckling prior to milking not only stimulates milk let-down but also prevents premature drying-off. Average liveweight at 12 months of age for Simmental-Tswana and Tswana calves were 147 kg and 124 kg, respectively. Unlike dry season weight losses experienced by adult cows the calves gained weight throughout the year.

Table 10. Monthly liveweight of Simmental-Tswana (SX) and Tswana (TS) calves (1985-86).

Breed	No.	Birth weight	Live weight for age in months
			1	2	3	4	5	6	7	8	9	10	11	12
SX	7	34	43	55	75	86	97	105	111	119	129	133	141	147
TS	25	28	35	43	49	60	72	82	92	102	110	115	119	124

Conclusion

The feeding system for in-calf and lactating Simmental Tswana crossbred and Tswana cows is based on local feed resources. The dry season feeding strategy using high protein farmer-grown lablab hay (Lablab purpureus) in association with crop byproducts and residues has been a significant intervention in small-scale dairy farms in Botswana. Despite low seasonal rainfall 30 dairy farmers participating in the project harvested and stored 34.1, 56.4 and 7.2 tons dry matter of lablab hay, sorghum/millet stover and sorghum chaff/husks, respectively.

The study demonstrated that there was no significant effect (P>.05) of single superphosphate (10.5%) application on dry-matter yield of lablab in both farmers' and on-station trials. However, wide variations in lablab and crop stover yields were observed within and between farms and project local e localities.

Chemical analysis results showed that on average lablab hay and cowpea stover contained 2.5 times more crude protein than sorghum and millet stovers. When lablab and cowpea whole plants were partitioned into leaves, stems and twines and roots; the dry-matter and nutrient contribution of leaves was higher than stems and twines.

A comparative (on-farm) feeding trial based on sorghum stover supplemented with either lablab or sorghum bran showed that under farmers' management conditions Simmental-Tswana crossbred cows produced 2.25 more milk per lactation than Tswana cows.

References

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APRU (Animal Production Research Unit). 1986. Livestock and range research in Botswana, Annual Report 1985-86. Government Printer, Gaborone, Botswana.

DPR. 1987. Dairy Project Annual Report, 1986-87. Animal Production Research Unit, Gaborone, Botswana.

Haque, I.; Nnadi, L.A. and Mohamed-Saleem, M.A. 1986. Phosphorous management with special reference to forage legumes in sub-Saharan Africa. In: I Haque, S. Jutzi and P.J.H. Neate (eds), Potentials of forage legumes in farming systems of sub-Saharan Africa. Proceedings of a workshop held at ILCA, Addis Ababa, Ethiopia, 16-19 September 1985. ILCA, Addis Ababa, Ethiopia. pp. 100-119.

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