A Review on Cattle Reproduction in Bangladesh
Cattle among other livestock species available are the most versatile component in relation to existing integrated agricultural farming system in Bangladesh. About 90% of total 24.5 million cattle are of non-descript indigenous in origin along with 10% crossbred constitute national herd. Among indigenous cattle (Zebu) in different region non-descript Deshi, Pabna, Red Chittagong and North Bengal Grey are predominant. The reproductive performance of these cattle and other crossbred are poor. Indigenous Pabna cattle attain puberty relatively earlier than other types. It is found that about two services are required for conception. Average calving interval ranged from 365-536 days and average postpartum service period is ranged from 103-161 days among the indigenous and crossbred cattle. Anestrus and repeated conception failure are major causes of the reproductive inefficiencies. Higher prevalence of Brucellosis is reported although its impact in cattle reproduction and human health yet to determine.
May 03, 2010; Accepted: June 03, 2010;
Published: August 05, 2010
Bangladesh lies in the Northeastern part of South Asia between 20024
and 26038 north latitude and 88001 and 92041 east longitude.
The county consists of low, flat and fertile land except the hilly regions in
northeast and southeast. The mean annual temperature is about 26°C with
an extreme range between about 4 and 43°C. The average annual rainfall varies
from 1429 to 4338 mm. The 80% of the rainfall occur in Monsoon covering July
to October (BBS, 2002). Cattle among other livestock species
available are the most versatile component in relation to existing integrated
agricultural farming system in Bangladesh. Total cattle population of the country
is about 24.5 million, which is about 1.79% of the world and 5.47% of Asian
cattle population (FAO, 2004a). In the last 10 years,
the cattle population has increased by 0.3% in contrast with 0.4% of the world.
Number of cattle per livestock household is 3.5 and that of 0.94 for all household
(BBS, 2002). Along with indigenous/local zebu cattle some
exotic and their crosses (not exceeding 10%) constitutes the national herd.
Among the indigenous types (Mason, 1988), non-descript
Deshi, Pabna, Red Chittagong, North Bengal Grey are predominant. Smallholder
farmers maintain majority of the animals that are generally maintained on crop
residues and other agricultural by-products. Rice straw is the basic feed item
satisfying over 80% roughage needs throughout the country. Grazing animals on
roadside, fallow land, riverbank or on lands from where crops has harvested
partially fulfilling the green roughage requirement. Whereas in some milk pocket
areas (Bhaghabarighat, Sirajgong; Takerhat, Faridpur etc.) green fodder are
available from November to April and next of the year animals are raised on
rice straw and preserve fodder. Rice polish, wheat/pulse bran etc as concentrate
sources are playing important role in livestock enterprises throughout the country
in variable level. In hilly areas, no attention is thrown for nutritional management
except in few cases when cattle are reared for milk yield. In farm conditions
improved feeding and management practices are followed throughout the year.
Several attempts have been taken scatterly to increase reproduction potential
of Bangladeshi cattle for different periods with variable achievements. Therefore,
the aim of this review is to summarize the information available on cattle reproduction
so that it would be helpful for designing future reproduction and improvement
strategy in the country.
The main goal in a commercial dairy operation is to optimize calf production
per cow as economically as possible. It is well established that maintaining
a satisfactory fertility level is the fundamental aspect for successful operation
of any cattle breeding program. In Bangladesh, around the year a large number
of animals remain barren or unproductive having exposed many times for natural
mating or artificial insemination and become a burden for the farmers. Table
1 shows the reproduction performance of indigenous and crossbred cattle
of Bangladesh. Indigenous Pabna cattle attain puberty relatively earlier than
other types. It was found that the same number of services is required for conception
and gestation length more or less similar for all types of indigenous and crossbred
cattle. The average calving interval ranged from 365-536 days among the indigenous
and crossbred cattle. The lowest and highest calving interval recorded in Red
Chittagong and non-descript Deshi respectively. The average postpartum service
period is ranged from 103-161 days in indigenous and crossbred cows. The results
indicated that the reproductive performance of cattle of Bangladesh is not satisfactory.
Rahman et al. (2009) found higher prevalence
of mastitis (19.9% in dry and 44.8% in wet seasons) in cows of Bangladesh. Parveen
et al. (2001) characterize Staphylococcal isolates of cows and concluded
that gentamicin, chloramphenicol and erythromycin could be of better value in
treating cows with the infections.
|| Reproductive performance (superscripts are the shortcut of
the references) of cattle in Bangladesh
|#Farming system, 1Majid et
al. (1995), 2Sultana and Bhuiyan
(1997), 3Hossain and Routledge (1982),
4Udo et al. (1990), 5Al-amin
et al. (2007), 6Ghose et al.
(1977), 7Al-Amin and Nahar (2007),
8Shamsuddin et al. (2006b), 9Sarder
(2006), 10Rahman and Haque (2001),
11Habib et al. (2003), 12Ahmed
and Islam (1987), 13Khan et al.
(1999), 14Alam et al. (2008),
15Mondal (1998), 16Rahman
et al. (2001), 17FAO (2004b)
Many farms in Bangladesh are so small that only one cow can be kept. Cows are
tethered in a stable or on available grazing land. They are used for draught
work as well as milk production. These management practices promote the occurrence
of post-partum anoestrus and limit behavioural manifestations of oestrus (Shamsuddin,
1995). This is explained by the fact that in intensive farming or in small
holdings having one cow, oestrus cannot be detected by primary signs such as
standing to be mounted as the cows are always tied up. However, the main weakness
affecting the accuracy of oestrus detection is that farmers are missing or misinterpreting
or are unaware of secondary signs of oestrus such as mucus discharge and swollen
vulva (Shamsuddin et al., 2006a). Detection of
oestrus and of the return to oestrus after unsuccessful artificial insemination
(AI) is clearly difficult under such conditions and inefficiencies have been
documented (Shamsuddin, 1995). Traditionally, pregnancy
diagnosis is not carried out as part of the artificial insemination programmes.
Generally suckling and weaning is not controlled in dairy production system
in Bangladesh. The adverse effects of the duration and frequency of suckling
on the initiation of post-partum cyclicity was studied by Shamsuddin
et al. (2006a). In a different study, they found an increased interval
from calving to first service and to conception due to frequent suckling (Shamsuddin
et al., 2001).
The main constraints of cattle reproduction is prolonged postpartum intervals
to conception and low Conception Rate (CR), which were the results of inefficiencies
in the management of nutrition, oestrus and Artificial Insemination (AI) services
(Shamsuddin et al., 2001). An economic opportunity
survey showed that management improvements directed towards increasing milk
production, increasing lactation length, decreasing age to first calving, decreasing
calf mortality and decreasing calving interval could increase income by $329-807
per farm per year, depending on the location (Shamsuddin
et al., 2006b). A participatory rural appraisal demonstrated that
the main demand of farmers was for on-farm services that would address feeding,
health and problems related to reproduction and that the resulting increased
income would enable farmers to pay for such services (Shamsuddin
et al., 2007). Missing one oestrus extends the calving interval in
cows and the age at first calving in heifers by 21 days and it is estimated
economic losses of $43 and $11 occur when there is a delay of 21 days in age
at first calving and calving interval, respectively (Shamsuddin
et al., 2006b). Ovarian cyclicity was evaluated by assaying progesterone
in two milk samples collected every month at 10 day intervals, showed that 40%
of postpartum cows were not detected in oestrus when they completed one or more
ovarian cycles (Shamsuddin et al., 2001). Another
important issue is that AI technicians often state that a cow is in oestrous
when she is not. In their earlier studies 30% of cows were stated to be in oestrus
when they were not (Shamsuddin et al., 2001). In
that study, 100% of cows with low level of progesterone in milk by day 21-24
were found not to be pregnant at later per rectum examinations. Such estimation
on day 22-24 after AI can be effectively used to identify non-pregnant cows
once the participation of farmers and inseminators is ensured by appropriate
motivation programmes (Shamsuddin et al., 2001).
NUTRITION AND REPRODUCTION
Puberty is a stage when replacement heifers manifest estrus signs and ovulate
for the first time. Nutrition is a major determinant of when puberty occurs.
Nutrition related infertility (also called sub-fertility) in dairy animals can
cause delayed puberty in heifers and prolonged calving interval in mature cows.
For example, with good nutritional management crossbred heifers can be bred
at 15-18 months. The age at puberty of zebu cattle in South Asia varies from
24-36 months (Mukasa, 1989). However in a study of 1440
smallholder dairy farms in Bangladesh, the age at first calving varied from
33-40 months, depending on the area studied, irrespective of cattle breeds and
nutrition on the best 20% of farms (Shamsuddin et al.,
2006a). This author estimated a yearly economic gain of USS$561 for a farm
with 3.6 crossbred heifers, if the heifers could have an age at first calving
of 37 months. Nutritional effects of puberty and sexual maturity is initiated
prenatally and continues through postnatal and post weaning development of heifers
(Shamsuddin and Aryal, 2009). In typical production system
of Bangladesh, calves are allowed to suckle only to stimulate milk letdown and
suckling often continues until the cow dries off. Since small dairy farmers
would prefer to increase net income from their dairy animals, little attention
is paid to calf nutrition. Calves are often fed poor quality milling byproducts
and crop residurs during their first 8-12 months of life when the reproductive
organs are developing. Replacement heifer management programs are rare in Bangladesh
and heifers are often fed surplus dairy cows feed. Anemia caused by parasitic
infestation or poor nutrition also delays sexual maturity in heifers. Weak or
silent heats occur in heifers due to underfeeding energy, phosphorus or vitamin
A. All these factors limit growth of heifers and delay their age at first calving
(Shamsuddin and Aryal, 2009).
The target of a dairy farm is to get one calf from a cow every year. The closer
a farm gets to this target, the better will be the economic return (Shamsuddin
et al., 2006a), but it is seldom achieved in the dairy industries
of Bangladesh. Other than cattle genetics, diseases, hot and humid climate and
underfeeding have all been claimed to prolong the calving interval. Postpartum
cows with poor body condition score often remain anoestrus for about a year,
which prolongs the interval from calving to first service and subsequently to
the next calving. Shamsuddin et al. (2006a) collected
data on body condition score (BCS) and estrus detection of postpartum cows in
smallholder farms and sampled milk from cows for measurement of progesterone
as an indication of corpus luteum development that follows ovulation. Cows with
lower BCS had longer intervals from calving to first ovulation and less detected
estrus than cows with a higher BCS. Similar reports are available on postpartum
cows brought for first service (Shamsuddin et al.,
2001; Siddiqui, 2008). Prolonged deficiency of energy
and protein in the diet can exert chronic stress on the hypothalamo-pituitary-ovarian
axis. Affected cows and heifers not only delay ovarian cyclicity, but also have
poor heat symptoms, which make oestrus detection and timing of breeding difficult
for the farmer and inseminator, which will bave negative effects on conception
rate (Siddiqui et al., 2002). Cows with low BCS
will have poor quality oocytes, which do not fertilize normally. Even if fertilized,
oocytes of poor BCS cows often do not sustain development to term. Oocytes of
heavy cows can be poor quality. For example, over conditioned cows had fewer
embryos than those with optimum BCS in a superovulation program (Siddiqui
et al., 2002). Cows fed a high energy diet on the day of breeding
will have a low chance of conception and high levels of glucose in the blood
at the time of early embryo development can be detrimental to embryos (Siddiqui
et al., 2002).
REPEAT BREEDING IN CATTLE
Repeat Breeder Cows (RBC) are a heterogeneous group of subfertile cows with
no anatomical abnormalities or infections that exhibit a variety of reproductive
disturbances in a consistent pattern over three or more consecutive heat cycles
of normal duration (17-25 days). One of the major constraints of profitable
dairy farming is low conception rate (Alam and Ghosh, 1994;
Shamsuddin et al., 2001). Early embryonic death
(<42 days) is a major factor in reproduction failure, which in turn causes
economic loss to the dairy industries (Rahman et al.,
1996). Shamsuddin (1995) reported 5% repeat breeding
cases in Bangladesh. Gani et al. (2008) found
positive correlation (r = 0.94) between repeat breeders and bacterial infection
of uterus. They detected bacteria in 62% repeat breeding cases in contrast to
only 28% bacterial infections from normal fertile cows where Staphylococcus
was predominant 37%, followed by Bacillus 35%, E. coli 29%,
Pseudomonas 18% while Gram negative minute rod shaped bacteria was 24%.
The isolates of Pseudomonas and Gram negative minute rod shaped bacteria
were obtained only from repeat breeder cows with mucopurulent uterine discharges.
Antibiotic sensitivity of their study showed moderate to high sensitivity to
amoxicillin, oxytetracycline and ciprofloxacin. Kamal et
al. (2010) found that double insemination with intrauterine antibiotic
improve conception in repeat breeding dairy cattle. Kamal
et al. (1999) was claimed fungal infection to be cause of repeat
breeding in cows and fungi belonging to Candida, Aspergillus were
predominantly isolated (26%) in varying proportions. Repeat breeding cows from
which Aspergillus were isolated had been suffering from endometritis
with mucopurulent utero-vaginal discharge. Alam et al.
(2007) also found bacteria and fungal infections in varying proportions
in repeat breeder cows of Bangladesh.
BRUCELLOSIS IN COWS
According to the Food and Agriculture Organization (FAO), the World Health
Organization (WHO) and the World Organization of Animal Health (OIE), brucellosis
is considered the most widespread zoonosis worldwide (Mustafa
and Nicoletti, 1995). In Bangladesh, brucellosis was first identified in
cattle in 1967 by Mia and Islam (1967) and human brucellosis
was first reported by Rahman et al. (1983). The
importance of brucellosis is not known precisely, but it can have a considerable
impact on human and animal health, as well as on socioeconomic impacts, especially
in which rural income relies largely on livestock breeding and dairy products
(Islam et al., 1983). In animals, the brucellosis
mainly affects reproduction and fertility, reduces the survival of newborns
and reduce milk yield. Mortality of adult animals is insignificant (Sewell
and Brocklesby, 1990). Rahman et al. (1983)
reported higher prevalence of brucellosis in cows of better managed farms and
estimated 12.8% human brucellosis in herders and agricultural workers. Rahman
et al. (2006) reported the seroprevalence of brucellosis in cattle
as 2.4~18.4% while the herd-level seroprevalence in cattle as 62.5% in Bangladesh.
Azimun (2007) reported the seroprevalence of brucellosis
as 4.5% in cattle and 6% in human. The overall seroprevalence of brucellosis
in cattle was 5% (Rahman et al., 2009) which
is higher than the overall seroprevalence of brucellosis (2%) reported by Amin
et al. (2004). Cattle aged more than 5 years age had insignificantly
higher prevalence of 7.69 and 2.56% than that aged below 5 years (Rahman
et al., 2009). The study stated that the higher prevalence of brucellosis
in cattle bred by natural breeding (5.72%) may be due to presence of infectious
bulls used for natural breeding (Rahman et al., 2009).
CONCLUSION AND RECOMMENDATIONS
Prenatal and postnatal nutrition is an important determinant of growth and attainment of puberty in heifers. Nutritional condition of a cow at calving and duration and frequency of suckling are important determinants to the initiation of ovarian activity. Postpartum cows divert a large amount of nutrient into milk making them prone to postpartum disorders and body condition loss. These delay postpartum onset of ovarian cyclicity. Dietary supplementation with vitamins and minerals of cow diet can help to improve their fertility. Heat detection efficiency should be improved by farmers training on oestrus detection. There is a need to introduce methods to determine the status of cows with respect to cyclicity and pregnancy in association with artificial insemination programmes. Determination of progesterone in milk on day 21-24 is a good means of making decisions on pregnancy by diagnosing the non-pregnant state with high accuracy. Breeding bulls should be regularly screened out following a standard bull health protocol. The traditional hospital based emergency veterinary service should be changed to an on-farm production-oriented one for delivering services on nutrition management, health and reproduction through the farmers cooperatives.
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