A. E. Khalid, and A. M. Awadelkarim.
SUMMARY
40 mature Nubian goats were selected and divided on a weight and age basis into four groups of 10 does each. The four groups were allocated at random to one of the following treatments:
- Group A were suckled their kids for 6 weeks
- Group B for 8 weeks
- Group C for 10 weeks
- Group D for 12 weeks
Lactation length of milk and milk production were determined for each animal.
The mean daily milk yield was 1.58, 1.21, 1.21 and 1.09 Kg for group A, B, C and D, respectively.
The mean maximum yield per day was 2.99, 2.19, 2.12 and 2.19 Kg for group A, B, C and D, respectively, reached during the period between 12 – 33, 10 – 34, 9 – 107 and 8 – 72 days of lactation, respectively. The total milk yield per lactation of the four experimental groups was 240.79, 179.63, 196.59 and 181.01 Kg for group A, B, C and D, respectively. The analysis revealed high significant (P<0.01) difference among the total yields per lactation in the four groups.
The mean lengths of lactations were 152, 148, 162 and 166 days for group A, B, C and D, respectively. The length of lactation tends to increase as suckling extend. Statistical analysis of the data showed no significant (P> 0.05) difference among the four groups.
INTRODUCTION
The goat was believed to have been the earliest ruminant to be domesticated (Zeuner, 1963).
Today half the population of the world is still drinking goat’s milk and even in affluent societies new interest in goats is developing because of the dietetic qualities attributed to goat’s milk products (Consantinou, 1985).
The Sudan Nubian goat has been and currently is used in several traditional production systems, as a multipurpose breed providing milk, meat, hair and skins. Much of the production data on this breed has been collected from government or universities research stations. Research pertinent to assessment of reproductive and productive potentials of the Sudan Nubian breed are however scant under traditional management system.
The aim of the present work was to provide more information on the effect of different suckling regimes on yield and length of lactation.
MATERIALS AND METHODS
The experiment was carried out at the Small Ruminants Unit, Animal Production Research Center, Kuku, and Khartoum North.
Four mature bucks and 70 Nubian goats were purchased from Abu-hamed Province, River Nile
State, and trucked to the experimental site. On arrival each individual animal was identified by ear tag and treated against internal and external parasites. Three weeks were permitted as an adaptation period before experimental data was considered. From above herd 40 mature goats were selected and divided on a weight and age basis into four groups of 10 does each. The four groups were allocated at random to one of the following treatments:
- Group A were suckled their kids for 6 weeks (each animal suckling single kid).
- Group B for 8 weeks.
- Group c for 10 weeks.
- Group D for 12 weeks.
Each group was housed separately offered food once daily and allowed free access to water The data was collected on day one of lactation, and continued up to the end of the lactation After kidding and expulsion of the placenta the does and kids were taken to a group pen where they were weighed, kids were ear tagged and in addition to birth weight, the sex of the kids was recorded.
The kids were left with their dams for 7 days, to provide an adequate quantity of colostrum. Then they were separated from their dams, and allowed to suck twice per day till weaning.
Fresh Medicago sativa (Barseem) and a concentrate ration containing 600 gm ground Dura (Feterita), 380 gm cotton seed meal and 20 gm mineral/vitamin premix per Kg were offered daily, at least 10% in excess of intake. The refusals were discarded daily and recorded. Then the feed intake of each group per lactation was determined.
Total lactation yields were collected by weigh – suck – weigh techniques following procedures out lined by Jenkins and Ferrell (1984). A – 24 – h milk production was estimated as follows:
A kid was weighed, allowed to suckle freely to satisfy, and then reweighed. The difference in the pre and post suckling gave an estimate of milk suckled. The remaining milk, if any, was removed by hand milking and weighed. This together with the suckled milk comprises a 12-h production. The same procedure was adopted in the evening give the other 12-h yield both yields were considered as the 24-h milk yield. This procedure was repeated every day till weaning. Following weaning the does were hand milked twice a day till dry. This procedure of 24-h milk yield was used to estimate parameters descriptive of lactation curves and allowed to predict time of peak lactation and total yield of milk for individual doe during the lactation. Also length of lactation was determined for each doe.
The data were analysed by analysis of variance for a randomized block design, and significant differences between treatments detected by least significant difference (Snedecor and Cochran, 1980).
RESULTS
The ingredients and chemical analyses of the concentrate mix offered to the experimental groups of goats is given in table 1.
Table 1. Formulation and composition of the concentrate mix for dams (on DM basis).
| Ingredients % | Composition % |
| Sorghum grains 60 Cotton seed cake 38 Mineral / vitamine mix 2 | Dry matter 96.20 Crude protein 21.95 Ash 5.02 Ether extract 6.60 Crude fiber 7.00 |
Table 2 provides data on mean dry matter intakes of concentrate and green fodder (Medicago sativa) kg per head per month throughout lactation period. Concentrate intakes were higher for all groups compared with green fodder intakes. The intake of goats immediately after kidding was low (19.70, 13.95, 16.21 and 14.76 Kg) for concentrate, and (3.47, 3.30, 4.95 and 4.15 Kg) for green fodder at the first month of lactation. At the 2nd month of lactation the intake reached the maximum level.
The first month of lactation. At the 2nd month of lactation the intake reached the maximum level (39.60, 27.90, 32.40 and 29.52 Kg) for concentrate, and (6.74, 6.60, 9.90 and 8.28 Kg) for green fodder for groups A, B, C and D respectively. Following that the intake decreased gradually till the end of lactation. The milk yield of goats was positively correlated with feed intake.
The data in table (3) portrayed the milk yield of the experimental groups at different levels of the production cycle. The highest mean daily milk yield (1.58 Kg) was obtained from group A, while the least value was secured by group D. Group B and C produced intermediate yields of 1.21 Kg for each.
The mean maximum daily yield followed approximately the same trend whereby the highest mean maximum daily yield was recorded in group A (2.99 Kg). Groups B and D maintained intermediate values of 2.19 Kg while the least value (2.12 Kg) was obtained in group C.
The data in table (3) also showed the days to peak yield. The figures indicated 12 – 33, 10 – 34, 9 – 107 and 8 – 72 as the intervals to peak yield for group A, B, C and D, respectively.
Table 2. Mean dry matter intakes (kg) per head per month.
| Month of Feed | Groups | |||
| lactation | A | B | C | D |
| 1st Concentrate | 19.70 | 13.95 | 16.21 | 14.76 |
| Barseem | 3.47 | 3.30 | 4.95 | 4.15 |
| 2nd Concentrate | 39.6 | 27.90 | 32.40 | 29.52 |
| Barseem | 6.74 | 6.60 | 9.90 | 8.28 |
| 3rd Concentrate | 35.48 | 5.11 | 29.20 | 26.58 |
| Barseem | 6.25 | 5.94 | 8.92 | 7.74 |
| 4th Concentrate | 29.57 | 20.62 | 24.33 | 22.14 |
| Barseem | 5.27 | 4.95 | 7.53 | 6.22 |
| 5th Concentrate | 28.78 | 19.53 | 22.71 | 20.67 |
| Barseem | 4.86 | 4.60 | 6.80 | 5.80 |
| 6th Concentrate | 25.00 | 18.50 | 21.08 | 19.19 |
| Barseem | 4.50 | 4.30 | 6.54 | 5.33 |
| 7th Concentrate | 19.00 | 13.98 | 16.26 | 14.78 |
| Barseem | 3.62 | 3.33 | 4.90 | 4.24 |
| Total intake Concentrate | 197.13 | 139.49 | 162.19 | 147.64 |
| Barseem | 34.71 | 33.02 | 49.54 | 41.49 |
| Cost, Sudanese Dinars | 8507.2 | 6724.7 | 8747.8 | 7662.6 |
When the total milk yield was partitioned to weekly yields, the data indicated that the highest yield during the second to the sixth weeks was secured by group A (17.10 Kg) followed by group B (12.21Kg). Group C and D maintained yields of 11.11 and 11.24 Kg, respectively. The subsequent yields during the 7th to the 12th week were 12.37, 8.67, 9.73 and 9.70 Kg for the four groups, respectively.
The corresponding values of yield tend to decrease as lactation progresses whereby the values during the 13th to 28th week of lactation were 5.07, 4.16, 5.17 and 4.16 Kg for group A, B, C and D, respectively.
Table 3. Milk yield of goats during lactation.
| A | B | C | D | ||||||
| The mean milk yield, kg/day | 1.58 | ||||||||
| The mean maximum yield, kg/day | 2.99 | ||||||||
| Days to peak yield | 12-33 | ||||||||
| The mean milk yield per week, kg at different stages of lactation | |||||||||
| 2–6 weeks of lactation | 17.10 | decrease % | 12.21 | decrease % | 11.11 | decrease % | 11.24 | decrease % | |
| 7-12 weeks of lactation | 12.37 | 27.6% | 8.67 | 28.9% | 9.73 | 12.42% | 9.70 | 13.7% | |
| 13-28 weeks of lactation | 5.07 | 59% | 4.16 | 52% | 5.17 | 46% | 4.16 | 57% | |
| Total suckled milk (kg) | 40.60 | 45.58 | 64.62 | 83.13 | |||||
| Total marketed milk (kg) | 200.19 | 134.05 | 131.97 | 97.88 | |||||
| Total milk yield per lactation (kg) | 240.79 | 179.63 | 196.59 | 181.01 | |||||
| Price (Sudanese Dinars) | 27088.9 | 20208.4 | 22116.4 | 20363.6 | |||||
Considering the percentage decrease in milk yield as lactation progress linked to the weaning protocols adopted in the experiment (6, 8, 10 and 12 weeks), it was evident that there was a decreased rate of % drop in milk yield with extended suckling. In other words suckling periods were inversely proportional to % drop in milk secretion indicating that suckling promotes persistency of lactating goats.
The % drop in milk yield for the four groups was 27.6%, 28.9%, 12.42% and 13.7% for groups A, B, C and D which were suckled for 6, 8, 10 and 12 weeks, respectively.
The total milk per lactation produced by the four experimental groups was 240.79, 179.63, 196.59 and 181.01 for group A, B, C and D, respectively (Table 4). The analysis revealed high significant (P<0.01) difference among the total yields per lactation in the four groups.
The milk sucked was 40.60, 45.58, 64.62 and 83.13 Kg for group A, B, C and D, respectively. The remainder milk after suckling (200.19, 134.05, 131.97 and 97.88 Kg) represent marketable milk for group A, B, C and D, respectively.
The data in Table (4) showed the milk yields per lactation for the four experimental groups. The highest milk yield was obtained by animal No. 2 in group C (377.95 Kg), and the least yields were recorded by animals No. 7 and No. 6 (112.40 Kg) in groups B and C, respectively.
The highest mean milk yield per lactation was recorded in group A (240.79 Kg) while the least value (179.63 Kg) was obtained in group B. Groups C and D produced intermediate yields 196.59 and 181.01 Kg, respectively.
The data in Table (5) showed the length of lactation per days for the four experimental groups. The longest lactation (221 days) was secured by the animal No. 2 in group C, while the shortest lactation (113 days) was shown by the animal No. 5 in the same group.
The mean lengths of lactations were 152, 148, 162 and 166 days for groups A, B, C and D, respectively. The length of lactation tends to increase as suckling extend. Statistical analysis of the data showed no significant (P>0.05) difference among the four groups.
Table 4. Milk yield per lactation (kg).
| Animals * A B C D Significance |
| 1 232.90 118.50 320.20 191.60 2 263.85 227.80 377.95 140.8 3 333.55 237.70 186.46 144.05 4 212.25 157.60 103.15 209.45 5 207.15 143.60 133.30 242.60 ** 6 232.60 200.95 112.40 169.65 7 272.65 112.40 141.25 148.10 8 196.65 206.80 262.85 249.10 9 223.60 165.50 188.45 148.10 10 232.65 157.60 139.85 166.60 Average 240.79 179.63 196.59 181.01 |
* Each group contains a set of different animals.
** Significant at p<0.01
Table 5. Length of lactation (days).
| Animals A B C D significance |
| 1 167 122 173 154 N.S 2 190 178 221 136 N.S 3 184 155 158 131 N.S 4 124 89 141 180 N.S 5 155 159 113 168 N.S 6 120 143 177 198 N.S 7 126 165 190 184 N.S 8 134 183 141 172 N.S 9 193 140 174 185 N.S 10 124 142 135 149 N.S Average 152 148 162 166 N.S |
N.S = not significant (P> 0.05)
DISCUSSION AND CONCLUSION
The lactation performance of the experimental goats portrayed in this study indicated higher milk yield when compared with those reported by El-Naim (1979), Kudouda (1985), Khalaffala and Suleiman (1990) and Tewfik (1997). The discrepancy in milk yield may be referred to the different environmental, nutritional and managerial conditions adopted in the different studies. It was observed that immediately after weaning there was a decline in milk production in the four experimental group. The rate of decline was higher in the short suckling groups (A and B) compared to the long suckling groups (C and D). The short suckling group reached their peak lactation yield earlier than the prolonged suckling group. This could be attributed to the suckling stimulus. Similar postulations were reported by Louca and others (1975) and Zygoyiannis (1987).
In conclusion, the results obtained in this study indicate that suckling duration may one of the many factor which influence the milk yield and lactation length traits of lactation animal. The suckling process is a strong stimulant for secretion and excretion of milk which will permit the Nubian goat to exhibit her full lactation potential. The farmers income can be increased markedly by decreasing the amount of milk consumed by suckling kids.
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