dairy cow

1. 4.9 WEANING OF CALVES
Definition
To remove a young animal from its dam so that it no longer feeds on
dam’s milk
With artificial reared calves, it simply means to stop feeding milk or
skim milk or milk replacers so that the calf entirely depends on
pastures and concentrates.
Calves can be weaned individually or in a batch eg. Calves born in a
week
When to wean a calf depends on:
The farm tradition: Mpwapwa- 2.5 months; Uyole – 3.5 months and
DASP – 3 months. NO clear justification!!
Generally, the aim should be to wean calves as early as possible so
that milk is used for human consumption.

2. When to wean a calf contd..
The weight and physical condition of the calf; delay weaning
when the calf is in poor condition, stunted, pot bellied
Economics of calf rearing and future use: NOTE it is expensive
to feed milk for a long time.
– destroy day-old bull calves !!!!
- wean later heifer calves and early for bull calves
Feeding system practiced at the farm; early introduction of
calves to pastures and concentrates is advocated.
Breed: Large breed calves grow faster and can be weaned at 5
weeks BUT requires high level of feeding. Small breeds like
Jersey have small birth weights, grow slowly; wean later.

3. When to wean a calf contd..
 Weight should be a better criterion for weaning. Too early weaned calves
have:
- Higher weaning stress
- Poor post-weaning growth performance
- Easily succumb to minor disease problems
CALF MORTALITY
Is the loss of calves through deaths. It could be pre-natal or post natal.
Pre-natal: Abortions; are deaths of foetuses before 270 days of gestation.
Still-births: Are peri-natal deaths at over 270 days of gestation and during the
first 24 hours of life.

4. CALF MORTALITY contd..
• Abortion rate = No. of abortions/ Total no. of pregnancies
/calvings
• Rate of still-birth= No of peri-natal deaths/ Total no. of calves
born
• Post-natal deaths:
Pre-weaning death rate= No. of calves died before weaning/No
of calves born alive or at risk
Post-weaning death rate = No of calves died from weaning to a
designated age/No of calves weaned or at risk

5. Why is calf mortality an issue of concern?
It reflects how good your farm management is. The farmer or
farm manager should take serious measures in managing
calves.
Herd size will not grow and consequently no culling of poor
cows can be practiced.
It indicates poor adaptability of the animals you possess to the
environment and endemic diseases in the area.
High death rate may indicate that your herd has health
problems. Can you identify those and eliminate them?? Good
recording can assist.

6. Why is calf mortality an issue of concern?
High death rates are associated with reduced income and increased
veterinary expenses i) Imagine a calf dies at 3 months of age.
How much revenue would you loose from milk alone? 4 l/day x 90
days x 400/= per litre = 144,000/= + labour + concentrates + vet
care!!
ii)If you have high death rates then you also spend a lot of money on
vet drugs.
 You loose animals of high genetic value eg. An F1 x Friesian = ¾
Friesian and ¼ Zebu
Rates recorded in the tropics:
- Abortions: 1.8 to 21.5%
- Still-births: 2.2 to 8.6%
- Calf mortality: 2.0 to >65%

7. Factors influencing calf mortality rates
 Decreases with age; higher pre-weaning than post-weaning
 Males calves die more then heifer calves b’se of preferential
treatment in feeding, management, late weaning and higher
economic value of heifers
 Varies with breeds and location
 Management system practiced, herd size, level of supervision,
liquid milk feeding system, design of calf pens
 Year and seasonal variations: pasture availability, weather,
disease incidences, personnel changes

8. Major causes of calf deaths
Diarrhoea esp. those caused by scours ( E. coli)
Pneumonia
Nutritional deficiencies; energy, protein, minerals
Tick-borne diseases; ECF, Anaplasmosis
Navel infection
Born weak; poor feeding during late gestation period
Bloat (tympanites), high feeding on legumes or grains
Others with low incidence rates; poisoning, snake bites, sudden
deaths, etc.

9. 5. RAISING REPLACEMENT
HEIFERS
5.1 Weaning to one year of age
oEnsure they have a sustained growth at LEAST cost.
It is important to monitor growth rates by monthly
weights or heart girths
oThey should be fed good quality roughages.
Supplement them with hay or silage and/or
concentrates in the dry season. After weaning,
concentrate supplementation is a must. Provide
minerals so that they get enough Ca and P.
oVaccinate against brucellosis using S19 vaccine at
about 6 months of age.

10. 5.2 From 1 to 2 years of age
• The basal diet should continue to be good quality roughages
(pastures, hay, silage) plus ample water.
• The feeding regime should aim at:
- Growing heifers to attain breeding weight at 15 months of age,
so that they can calve at about 2 years of age.
- For small breeds like Jersey, growth rate should be around 0.5
kg/day
- For large breeds (Friesian, Ayrshire and Brown Swiss), growth
rate should be 0.8 kg/day
- Calving heifers should attain 80 – 90% of their mature size

11. From 1 to 2 years of age contd.
• Making sure that heifers calve viable calves and are capable of
producing milk to their full genetic potential.
• Recommended weights at mating for different breeds:
Large breeds (Friesian, Brown Swiss and Friesian x Boran
crosses). Mate them at 300 to 350 kg at 14 to 16 months of age.
Small breeds (Ayrshire, Sahiwal, Jersey andtheir crosses). Mate
them at 230 to 275 kg when around 13 to 15 months of age.

12. Effects of under feeding heifers
1. Delay in the on-set of puberty which occurs when calves have
attained 40% of their mature body wt. Age at puberty is
inversely related to growth or plane of nutrition.
2. Such heifers become smaller in size at calving. Slightly
underfed heifers may recover after calving.
3. Have slightly more incidences of difficult calvings. Risk of
abortion are also higher due to competition for nutrients
4. Less influence on conception rate but more missed or silent
heats

13. Effects of under feeding heifers contd..
5. Will have poor first lactation yield because of competition for
nutrients for growth vs milk production. Subsequent
performance will depend on feeding level after calving.
Effects of over-feeding heifers
a)Because of fast growth & early breeding, such heifers are likely
to have dystocia: i) Large size of calf and foetal membranes. ii)
Less developed pelvic opening
b)They tend to show stronger signs of heat but fertility may be
low.
c) Because of good body condition and body reserves, they
produce more milk of higher BF content

14. Effects of over-feeding heifers contd..
d) They may develop fatty udders with limited secretory cells thus leading to low milk yields
e) Longevity (herdlife)is reduced due to early maturity and fast ageing.
305-day milk yields (kg) (After Little, 1975)
----------------------------------------------------------------
Management level Lactation number
1 2 3 Total
-------------------------------------------------------------------------------------
Rapidly reared, early bred 1863 2963 3536 8362
Rapidly reared, late bred 2427 3229 3431 9087
Normally reared, late bred 3885 4668 4807 13360
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15. Health management
Control tick-borne diseases by regular
dipping/spraying
In areas infested with tsetse flies, control
trypanosomosis (Berenil !)
Immunize /vaccinate for other common diseases:
- FMD, 2 times/year
- BQ, once per year
- Anthrax, once per year
- Lumpy skin disease, once per year

16. Other things
• Record matings to check for repeated heats. Do pregnancy tests
(PD’s)
• Remove extra teats (supra numerary teats) 6 to 12 months after
birth. A vet can asssist.
CONCLUSION
 A dairy heifer is the future milk producing machine. A 350 kg cow
can produce 4,000 litres of milk; > 10 times its weight in 10 months.
 Ideal rearing conditions are necessary in order to exploit her
production potential.