Reproductive and lactation performances of Ayrshire and Boran crossbred cattle kept in smallholder farms in Mufindi district, Tanzania

S W Chenyambuga and K F Mseleko

Department of Animal Science and Production, Sokoine University of Agriculture, P.O.Box 3004, Morogoro, Tanzania
chenyasw@yahoo.com   or   chenya@suanet.ac.tz

Abstract

This study was carried out to determine the reproduction and lactation parameters of Ayrshire x Boran F₁ crosses kept by small-scale farmers in Mufindi district, Tanzania. The study involved 48 small-scale dairy farmers located in six villages. The mean (± s.e.) herd size of the selected farmers was 3.7 ± 0.3. Data on breeding dates, calving dates, drying off dates, daily milk yield and deaths of calves were obtained from records kept by the selected farmers from 1997 to 2007. The data were used to compute age at first calving, calving interval, days open, number of services per conception, calf mortality, lactation milk yield, lactation length and dry period.

The overall mean for age at first calving (AFC) was 38.4 ± 0.5 months and for calving interval was 402.6 ± 3.0 days. The AFC was significantly (P ≤ 0.001) influenced by the season of birth while calving interval was significantly (P ≤ 0.001) affected by the year of calving and parity. The overall mean length of the days open period was 100.7 ± 3.6 days. Year of calving, season of calving and parity significantly (P≤ 0.05) affected the length of the days-open period. The number of services per conception was between 2 and 3. The overall calf mortality rate was 18.2% and was significantly (P ≤ 0.05) influenced by year of birth and sex of the animal. The overall mean lactation length was 287.7 ± 2.5 days. Lactation milk yield increased with parity from 1260.6 to 1760.5 litres in the first and fourth parity, respectively. Lactation length and lactation milk yield were significantly (P≤ 0.05) affected by year of calving and parity. The overall mean dry period was 107.5 ± 4.5 days. The dry period was significantly (P ≤ 0.05) affected by year of calving, season of calving and parity.

It is concluded that the performance of the Boran x Ayrshire crossbred cows in the study area is unsatisfactory due to advanced age at first calving, prolonged calving intervals, shorter lactation length, lower lactation milk yield and high calf mortality rate.

Keywords: Age at first calving, calf mortality, calving interval, lactation length, milk yield

Introduction

Efforts to develop the diary industry in Tanzania started in early 1960s, immediately after independence. The government efforts were aimed at increasing the population of improved dairy cattle in order to produce adequate amount of milk to meet the increased demand for dairy products within the country. Between 1960s and 1970s the government aim was to establish large scale dairy farms through direct importation of exotic dairy breeds, principally from temperate countries (Kurwijila 2002). The direct use of exotic breeds for production was faced with problems of lack of fitness, adaptability and resistance to various diseases and parasites, and hence little success (Mpiri 1990). After realizing that the use of pure exotic breeds was a failure, efforts were shifted to crossing dairy breeds with the Tanzania Shorthorn zebu (TSHZ) with the intention of upgrading TSHZ. The crossbreeding of the local cattle to temperate dairy breeds has been pursued as a means of increasing milk production in the country since mid 1960s to date. However, the performance of crossbred dairy cattle in large-scale parastatal farms was disappointing due to management problems, and hence, the envisaged dairy industry development was not achieved (Kurwijila 2002).  The poor performance of the large-scale parastatal dairy farms prompted the government to change the development strategy of the dairy industry towards small-scale production system (Mpiri 1990). The smallholder dairy sector is comprised by individual farmers owning a few dairy cattle, normally between one and ten animals (Swai et al 2007). By mid 1980s, smallholder production was encouraged and promoted not only as a means of achieving national self-sufficiency in milk and milk products, but also for poverty alleviation in rural areas (Kurwijila 2002). Consequently, from the mid 1980s, a number of smallholder dairy development programmes were initiated in various parts of the country. Performance evaluation studies revealed that the F₁ crosses of zebu cattle and dairy breeds perform better than their indigenous zebu and that further upgrading beyond 50% Bos taurus inheritance does not lead to appreciable improvement in the performance of high-grade cattle and often results are disappointing (Msanga 1994). To increase the supply of F₁ dairy cattle heifers to smallholder farmers, Livestock Multiplication Units (LMUs) were established. These LMUs were stocked with TSHZ or Boran cows for crossbreeding with sires of exotic breeds, mainly Friesian and Ayrshire. The F₁ heifers produced in the LMUs are usually sold to small holder livestock keepers or to Non-governmental organizations/Community based organizations, which in turn, distribute them to smallholder farmers.

In Mufindi district Small-scale dairy development programme started in 1978/79 under the Southern Highlands Dairy Development Project (SHDDP). The programme was aimed at improving the nutritional status and income of the rural population through promotion of dairy cattle production. Participating farmers in selected villages were trained on improved livestock husbandry and were required to establish one acre of improved pasture and build a cow barn. After fulfilling these conditions each farmer was given an in-calf F₁ heifer. The heifers were obtained from Sao Hill LMU located in Mufindi district. This LMU maintains Ayrshire and Boran and produces F₁ crosses for distribution to farmers. The performance of these crossbreds under farmers’ condition has not been evaluated. This study was carried out to determine the performance of Ayrshire and Boran F₁ crosses that are kept by the small-scale farmers in order to assess their suitability and determine the environmental factors that influence their performance in the study area. Since reproductive and lactation performances are the basis for a profitable dairy farming enterprise, reproductive parameters (age at first calving, calving interval, days open, number of services per conception and calf mortality) and lactation parameters (lactation length, lactation yield and dry period) were assessed.

Materials and methods 

Description of the study area

The study was conducted in Mufindi district, Tanzania. Mufindi district is located in Iringa region in the southern highlands of Tanzania. The district is located at an attitude that ranges from 1700 to 2200 m above sea level. The mean temperature is between 13.2 and 18.4^oC while annual rainfall ranges from 1200 to 1600 mm. The rain season starts in November and ends in May and it is followed by a cool dry period up to August. Medium and short grasses dominate the grasslands in the district.

Animals and their management

Data on reproductive performance and milk production of F₁ crosses of Ayrshire x Boran were used in this study. The animals were kept by small-scale farmers either under zero grazing, tethering or a combination of these systems with herded grazing. The animals were fed on established pastures (Elephant grass) and natural pasture. In the dry season, they were also fed on maize stovers. Milking cows were supplemented with either maize bran alone or a mixture of maize bran and sunflower seed cake (at a ratio of 3:1 maize bran: sunflower seed cake). All dairy cattle farmers in the study area used natural mating to breed their cows, either using project bulls or their own bulls. Most of the farmers were dipping or spraying their animals with acaricides once per week or once in two weeks to control ticks.

Data collection

Data used in this study were obtained from 48 small-scale dairy farmers located in six villages. In each village eight farmers who keep records were purposely selected from the list of dairy cattle farmers. The farmers were selected based on the criteria of owning F₁ crosses of Boran x Ayrshire and having complete records on individual animals. The average herd size (mean ± standard error) of the selected farmers was 3.7 ± 0.3.  The data on breeding dates, calving dates, drying off dates, daily milk yield and deaths of calves were collected from records kept by the selected farmers from 1997 to 2007. In addition, individual interview using a structured questionnaire was used to collect information on number of services per conception.

From the data collected reproductive and lactation parameters were computed. Age at first calving (AFC), calving interval, days open and number of services per conception and calf mortality rate were used as measures of reproductive performance while lactation milk yield, lactation length and dry period were considered as measures of lactation performance.  All parameters were computed from the records kept by the small-scale dairy farmers. The number of services per conception was obtained by asking the farmers the numbers of services a cow was mated to conception.

Statistical analysis

Analysis of variance for the data on age at first calving, calving interval, days open, lactation length, lactation milk yield and dry period was done using the general linear model of the SAS computer programme (SAS 2000). The model included fixed effects of year of birth/calving, season of birth/calving and parity. The data on calf mortality rate were analyzed using the chi-square test and the main factor assessed included sex, year of birth and season of birth.

Results and discussion 

Reproductive parameters

Reproductive parameters of the F₁ crosses of Boran x Ayrshire under small-scale production system are shown in Table 1.

The least square means for the period from birth to when a heifer calved for the first time ranged from 37.0 ± 1.7 to 39.6 ± 0.9 months, with a coefficient of variation of 12.2%. The observed age at first calving (AFC) is higher than the average AFC of 32 and 35.5 months which has been reported for Ayrshire crosses kept in Tanga region by smallholder farmers (Mulangila 1997)  and at a research station (Shekimweri 1982), respectively. However, the AFC values in the present study are within the range of 28.5 to 38.9 months that has been reported for various crossbred dairy cattle kept under smallholder production system in Tanzania (Kishinhi 1999). In this study AFC was significantly (P ≤ 0.001) influenced by the season of birth, but not by the year of birth. Animals born during the dry season calved for the first time earlier than those born in the wet season by about 5.4 months. This is in agreement with the observation by Asimwe and Kifaro (2007) who reported that AFC is influenced by the seasons in which the heifers are born. This is associated with seasonal fluctuation of feed availability and quality. The animals born in the dry season were weaned in the wet season in which there is abundant and good quality pastures, hence, the weaned calves got better nutrition and grew faster than those born in the wet season and weaned in the dry season which is characterized by inadequate and poor quality pastures.

The overall mean calving interval was 402.6 ± 3.0 days, with a coefficient of variation of 13.1% (Table 1). This value is lower than the calving interval of 454 – 479 days observed in Ayrshire crosses (50, 62.5 and 75%) by Mulangila (1997). It is also lower than the calving interval of 476 days observed in various crosses of dairy cattle by Swai et al (2007) in Tanga region. Moreover, the calving interval in this study is within the range of calving intervals (398 – 426 days) observed in Kenya for Ayrshire crosses (Kahi et al 2000; Migose et al 2006).  Although the calving interval in this study is lower than that found by other studies in smallholder farms (Mulangila 1997; Kishinhi 1999), it is beyond the target calving interval of 365 days in dairy cows. Calving interval in this study was significantly (P ≤ 0.001) affected by the year of calving and parity, but not by season of calving. The least square means for calving interval decreased with parity from 414.7 in parity one to 390.2 days in parity three. With regard to years, the trend was not regular. This reflects inconsistencies in breeding management between years, particularly on the time taken to mate the cows after calving. In addition, the influence of year on calving intervals may be due to changes in weather conditions, which in turn are associated with forage quality and quantity fluctuations.

The overall mean length of the days open period was 100.7 ± 3.6 days. The observed days-open period is shorter than that reported (134 days) by Balikowa (1997) in crosses of Boran and various dairy breeds.  The length of the days-open period in this study was significantly affected by year of calving, season of calving and parity. The longest days-open period (126.4 days) was observed in 1999 while the shortest was found in 2006 (78.9 days). The days-open period for the cows calved in the dry season exceeded that of the cows calved in the wet season by about 22 days. Cows in their first parity showed longer days-open period (121.8 ± 5.4) than those in the subsequent parities. Similar observation has been reported by Asimwe and Kifaro (2007) in dairy cattle kept in smallholder farms in Northwest Tanzania. According to Asimwe and Kifaro (2007) the decrease in days-open period with advancement in age is due to physiological stress experienced by the first calvers in early lactation.

According to the response of most farmers (87.5%) the number of services per conception (NSC) was between 2 and 3. The NSC reported by farmers is slightly higher than that observed by Shekimweri (1982) for 50% Ayrshire crosses (1.5 – 1.7 NSC) at Livestock Research Centre in Tanga region. The differences could be attributed to the failure of farmers to detect heat signs at appropriate time, as a result ovulation was missed for most of the time when the cows were taken to the bull, and this eventually influenced the NSC. However, the NSC in the present study compares well with NSC of 2.2 and 2.3 reported for crossbred dairy cattle kept under smallholder farms (Mureda and Zeleke 2007) and at a research station (Haile et al 2009), respectively, in Ethiopia.  

The overall calf mortality rate was 18.2%. The pre-weaning mortality rate in the present study is higher than that observed by Mulangila (1997) and Shekimweri (1982) for Ayrshire crosses kept in smallholder farms (11.7%) and at a Livestock Research Centre (8.8%), respectively. However, the mortality rate in this study is comparable to the calf death rate of 22% reported by Wudu et al (2008) in smallholder farms in Ethiopia.  The statistical analysis by chi-square test revealed that the pre-weaning mortality was significantly affected by year of birth (P ≤ 0.0001) and sex of the animal (P ≤ 0.05).  Calf mortality rate increased with years from 7.8% in 1999 to 56.5% in 2005. This reflects decline in management as years went on. It seems that during the initial years the farmers were keen and adhered to proper management practices as they were trained. However, as years went on, the farmers probably forgot what they were taught and hence poor management practices resulted, leading to high calf mortality rate. The mortality rate of male calves (21.5%) was greater than that of female calves (14.5%). This is a reflection of preferential treatment given to female calves compared to male calves. Similar observation has been made by Mulangila (1997). Although the effect of season was not significant (P> 0.05), slightly more calves died during the wet season (19.4%) than in the dry season (16.7%).

Lactation parameters

The results for lactation performance of the Ayrshire x Boran crosses under smallholder production system are shown in Table 2. 

The overall lactation length of 287.7 ± 2.5 days observed in this study is higher than that observed by Mulangila (1997) in 50% Ayrshire crosses (258 days) in Tanga region, but lower than that reported by Balikowa (1997) in F₁ Boran crosses (364.2 days) in Mbeya and Iringa regions.  It is also lower than the ideal lactation length of 305 days. However, the lactation length observed in this study is within the range (260.5 – 390.3 days) reported by Kishinhi (1999) in smallholder farms in Tanzania. In Kenya the lactation length for Ayrshire crosses has been found to range between 318 and 329 days (Kahi et al 2000). In the present study, lactation length was significantly (P≤ 0.05) affected by year of calving and parity, but not by season of calving. The length of the lactation period was found to increase with parities. Animals in their first parity had shorter lactation length by 60.4 days compared to those in the fourth parity. Lactation length decreased with years from 393.2 ± 27.1 days in 1998 to 241.5 ± 9.7 days in 2007. The lactation length of cows calved during the wet season exceeded of those calved in the dry season by about six days.

The overall mean for lactation milk yield was 1381.0 ± 17.1 litres. This value is lower than that of Aryshire crosses reported by Mulangila (1997) (1691 – 1812 litres) in Tanga region, Tanzania and by Migose et al (2006) in Kenya (2787 litres). Also it is lower than the lactation milk yield observed by Balikowa (1997) in F₁ Boran crosses (1742.6 litres) in southern highlands of Tanzania. Lactation milk yield was significantly (P< 0.001) affected by year of calving and parity. The highest lactation milk yield (2212.0 litres) was observed in 1998 while the lowest milk yield (1284.0 litres) was found in 2007. Lactation milk yield increased with parity from 1260.6 ± 31.4 in the first parity to 1760.5 ± 56.7 litres in the fourth parity.  This is in agreement with the observation made by Migose et al (2006) that milk yield in dairy cows increases with age as a result of a combination of  increased body weight and full development of secretory tissues. According to Migose et al (2006) the peak lactation yield in Ayrshire crosses is observed in the fourth lactation. 

Dry period was significantly (P ≤ 0.05) affected by year of calving, season of calving and parity. The dry period ranged from 42.4 in 1999 to 128.3 days in 2001.  Animals in their first parity had significantly (P ≤ 0.05) longer dry period than the cows in the subsequent parities. Cows calved in the wet season had shorter dry period than those calved in the dry season by about 22 days.  The dry period observed in the present study is lower than the dry period  of 187 – 217 days observed by Mulangila (1997) in Ayrshire crosses, but consistent to that reported by Fadlelmoula et al (2007) in crossbred dairy cows in Sudan. However, it is above the optimum dry period of 60 days recommended for dairy cows.

Conclusions 

• The present study indicated that the Boran x Ayrshire crossbred cows kept in the smallholder farms in the study area calved for the first time at advanced age, had prolonged calving intervals and high calf mortality rate, thus their reproductive performance is unsatisfactory. Similarly their lactation length is shorter than the expected lactation length of 305 days and lactation milk yield is relatively lower than the production levels reported in other parts of East Africa.

  
  

• Further detailed investigation is needed to examine the effect of farmers’ husbandry practices on the reproductive and lactation performances of crossbred dairy cows with the purpose of developing and subsequent implementation of appropriate intervention measures.

Acknowledgement 

The authors are indebted to the staff of the Southern Highlands Dairy Development Project for introducing the Boran x Ayrshire F_I crossbred dairy cows. We acknowledge the assistance and cooperation received from the Livestock Extension Officers and dairy cattle farmers in the study area.

References 

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Received 3 January 2009; Accepted 6 March 2009; Published 1 July 2009

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