B. A.BABlKER,F.A. AHMED AND H.A.M.ELHAG

Department of Animal Science. Favult y of Agricultural Sciences,

University 0f Gczira; P.O.Box 20, Wad Medani

SUMMARY

Four groups of Kenana X Friesian cross- bred calves were weaned at 6,8,l0 and l2 weeks of age.Concentrate starters and supplemmts based on agro industrial by-products together with forage sorghum was offered ad libiturn in the postwea- ning period from l2 to 26 weeks of age. The total dry matter, supplement , forage and liveweight gains were measured during this p:riod. Feed conversion ratio was calculated. No significant difference in total dry matter intake was observed. Calves weaned at 12 weeks of age had a significantly (P < 0.01) higher supplement intake than th: early weaned ones. Early weaned calves consumed more forage than late weaned calves. A highly significant (P < 0.001) liveweight gain and feed conversion ratio was shown by the six – week weaned calves. The results suggest that an early weaning system could be successfully adopted with a favourable post ~ weaning performance.

INTRODUCTION

        Early weaning of calves is widely practiced in developing countries as a tool for offering more milk for human consumption. A great deal of work has been carried out on its elfect on the subsequent performance of the animal ( Percival, 1951; Chambell, 1959; Aitken, Preston, Whitclaw, Macdearrnid and challeson. I963; Hamula and Morimoto, I965; Economides and Georghiades, 1983). ln the Sudan calf rearing is practiced more or less on a natural basis either in the form of suckle cows with calves under range conditions or in a form of restr- icted feeding. The former method is practiced in Western and Southern Sudan , in the Butana area in Eastern Sudan and to some extent in the southern parts of the Blue and White Nile Provinces. In these areas calves are weaned at the age of 6-9 months. Restricted suckling , on the other hand, is mainly practiced in small    holdings and farms around big cities like Khartoum and Wad Medani, where dairying is achieving much popularity. Under this system calves are allowed to suckle for various lengths of time on limited amounts of milk. Generally this continues for 4 – 6 months of age. To our knowledge no information has been reported on investigations carried out on early weaning of calves in the Sudan. Under tropical conditions, 0gund- ola (198!) successfully weaned calves at 3,5 and 7 weeks of age. It was reported that calves reared on larger amounts of milk gained more slowly after weaning due to their poorer reticulo-rumen development at weaning (Kaiser,l976; Econ- omides and Georghiades, 1983). For early weaning starters and supplements of concentrates are olfered from one week of age completely replacing the milk by the third to fifth week( Roy , 1980). The objective of the study reported here is to give information on early weaning ax a system to be adopted in farms and small holdings, to investigate the possib- ilities of using agro-industrial by» products and green forage as a substitute for milk and to lookinto the dry matter intake, livewight gain and feed conversion ratio of crossbred calves weaned at 6,8,l0 and l2 weeks of age and reared to 26 weeks.

MATERIALS AND METHODS

      Sixteen cross-bred ( Kenana X Friesian ) calves were used in this study. All the calves (9 males 7 females ) were born at the University Farm, Nisheishiba. Calving was prepared to be indoors and the dams were allowed to lick their calves clean and dry . The calves were then indentified in sequence and randomly alloc- ated to four treatments. The treatments were weaning age of 6, 8, l0 and 12 weeks. The calves birth weights were taken. They were then transfered to indivi- dual feeding pens, constructed from bamboo shoots, where they received colos- trum by nipple pail within one hour after delivery. The quantity of colostrum offered to each calf in the first six hours was 10% of its birthweight. Colostrum feeding at this rate continued for 48 hours. The calves were then bucket – fed for the following five days from their mothers rnilk. Later they were given milk from the farm pool. Milk was ofiered at the same rate as colostrum till weaning. The daily amount of milk was divided into two feeds gives: at 6.0 a.m and 5.0 p.rn. At the end of the first week the calves were provided with clean tap water. They were gradually introduced to cut forage sorghum ( Kan 70) and a concentrate    (starter ) ration till the age of twelve weeks. Thereafter and up to 26 weeks of age all calves received a loose meal ( supplement) containing the same ingredients of the starter. The composition of the starter and the supplements is shown in Table l. The ingredients were formulated to contain 175 and l55 g Crude Protein /kg DM for the starter and supplement respectively. 

 The chemical analysis was done according to the standard methods adapted by the A.O.A.C.(l975). Both the forage and the concentrates were ofl‘ered ad libitum. The daily dry matter intake was recorded. Fortnightly weights of the cab’/es were also recorded. After weaning, the calves were removed from the individual pens to larger pens accomodating the four calves of the same treatment. The calves were vaccinated against anthrax , haemorrhagic septicaemia, and rinderpest. They were sprayed with an acaricide every two weeks. The data statistically analysed by analysis of variance according to steel and Torrie ( 1960 ).

RESULTS AND DISCUSSION

The performance of thc calves weaned at 6.8, 10 and 12 weeks of age during the post – weaning period from l2 to 26 weeks of age is shown in Table 2. No significant difference was observed between the daily total dry matter intake by the calves in the four groups. However, there was a significant ( P < o. 05) dihe- rence in the dry matter intake of the concentrate supplement. Calves weaned at l2 weeks of age had a higher (P < 0. Ol) supplement intake than those weaned at si.=. weeks of age, but not significantly ditferent from the other two gl’0il_ps. The     forage sorghum intake by all groups was not significantly diflferent but there was a tendency for the early weaned calves ( 6 and 8 weeks) to consume more forage

 then the late weaned calves. Calves weaned at 6, 8 and 10 weeks of age had a sfgmfczmly (P < O. CO1) higher growth rate than those weaned at 12 weeks. The highest liveweight gain during the 14 – week period of study was shown by the group cfcalvcs weaned at 6 Weeks of age. Feed conversion ratio ( kg DM intake] lg l1\<v\'<igl_t grin ) follcwecl a sirnilar trend as the liveweight gain. Calves werred earlier (6 weeks) were significantly (P < 0.001) more efficient in converting the feed to body_ gain than the late weaned calves. The high forage intake by the early weaned calves could be explained by the fact that these calves developed the capacity to handle bulky feeds earlier than the late weaned ones. This is attributed to an earlier rumen development( Hamula and Mo1rimot0,l965). The higher liveweiglir gain and feed conversion ratio shown by the early weaned calves in this study is in agreement with that reported by Per-    eival (195 l) who found that early weaned calves made a good recovery at l2 weeks g of age with a subsequently better growth rates than late weaned calves. The poor growth rates by the late weaned calves may be due to the high quantities of milk consumed thus resulting in a limited rumen development ( Economide and Geor-. ghiades , 1983 ). The results of this study suggest that a six – week weaning system for calves based on starters and followed by supplements of agro-industrial by products could be adopted. This will reduce the amounts of milk offered to calves and will successfully prepare the calves for a better utilization of feeds and a high prod- uction in the post – weaning period. The economics of this system needs further detailed studies.

ACKNOWLEDGEMENT

We are grateful to members of staff on Nisheishiba Farm, University of Gezira. for their help in the care of the animals. One of us (B. A.B ) was on a study leave from the Ministry of Animal Resources. ‘

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