Studies on some non-genetic factors affecting reproductive performance of Holstein Friesian × Deoni crossbred cows

The present study was undertaken to evaluate the effect of non-genetic factors on reproductive performance of Holstein Friesian × Deoni crossbred cows. Data representing 256 HF × Deoni crossbred cows from cattle crossbreeding project with 1485 total records of lactation over a 30 years period were analyzed to determine the effects of period of calving, season of calving, age at first calving and parity on reproductive performance. The parameters used as indicators of reproductive performance in this study were age at first calving (AFC), days open (DO), dry period (DP) and inter calving period (ICP). The overall least squares mean of age at first calving (AFC), days open (DO), dry period (DP) and inter calving period (ICP) were 1198.54±8.18, 149.15±3.87, 126.90±1.76 and 422.95±2.53 days, respectively. All sources of variations except season of calving had significant effect on AFC and ICP. The AFC as seen in this study was somewhat longer. Cows calving in summer had reduced reproductive performance, as measured by DO and DP. First lactation cows had longer DO, DP and ICP, which were poorest values as reproductive traits. It is therefore concluded that, the reproductive performance of these crossbred cows is affected by some non-genetic factors and hence, additional reproductive strategies are needed to improve their performance.


INTRODUCTION
Reproductive traits are crucial factors in determining the profitability of dairy production (Lobago et al., 2007).The reproductive performance of the breeding female is probably the single most important factor that is a prerequisite for sustainable dairy production system and influencing the productivity.The size of the calf crop is all-important for herd replacement and the production of milk depends heavily on the cow's reproductive activity (Kiwuwa et al., 1983).Reproductive performance of cattle is influenced by feed, genetics, disease and management practices (ILCA, 1990).
In India there are about 37 breeds of cattle.In spite of the presence of large and diverse cattle genetic resources, the productivity of cows remains low in the country, for various reasons, such as inadequate nutrition, poor genetic potential, inadequate animal health services, the harsh climatic conditions and other management related problems.The milk productivity in India remains one of the lowest as compared to the many leading countries of the world.In the country, the average milk productivity of crossbred cows, indigenous cows and buffaloes is about 6.44, 1.97 and 4.3 kg/day, respectively (GOI, 2007).The indigenous cattle breeds are low producers; they mature late and have a delayed conception coupled with long calving intervals.The productivity of dairy animals could be increased by crossbreeding the low yielding non-descript cows with high yielding suitable exotic breeds.This, systematic crossbreeding of indigenous and temperate dairy breeds is principally undertaken to combine the high milk yield and early sexual maturity of European dairy breeds with hardiness, disease resistance and adaptability of zebu cattle.Thus, crossbreeding of local non-descript cattle with exotic breeds of high genetic potential is considered to be a rapid and effective method of improvement.
Deoni is an important indigenous cattle breed of India.These animals are mainly found in the Latur district and the adjoining area of Parbhani, Nanded and Osmanabad districts of Maharashtra.Deoni is a medium heavy animal.It is found in three-colour variations viz.Wannera (clear white with black colour at the sides of the face), Balankya (clear white with black spots on the lower side of the body) and Shevera (white body with irregular black spots).The body is moderately developed and symmetrical with distinct muscles.Deoni cattle are hardy and well adapted to their breeding tract and constitute an important cattle genetic resource of India.The breed was found to be hardy and well adapted to tropical draught prone areas.The animals are docile and calm.Traditionally, Deoni cattle are maintained under a semiintensive system of management.
Marathwada Agricultural University has taken a project for improvement of Deoni cattle breed by cross breeding local Deoni cows with Holstein Friesian.The success of dairy production in general and crossbreeding programmes in particular needs to be monitored regularly by assessing the productive and reproductive performance under the existing management system.The aim of the present study is, therefore, to investigate the effect of non-genetic factors on the reproductive performance of HF × Deoni crossbred cows kept at cattle crossbreeding project (CCBP).

Study area
This study was conducted at CCBP of Marathwada Agricultural University, Parbhani India.It is located at an altitude of 407 m above the mean sea level and is situated between 17° 35 ' N and 20° 40' N latitude and between 70° 40' E and 78° 15' E longitude.The mean daily maximum temperature varies from 29.1°C in December to 42.5°C in May.The mean daily minimum temperature varies from 6.9°C in December to 25.4° C in May.The relative humidity ranges from 11 to 90%.Normally the summer becomes hot and general dryness persists throughout the year except during south-west monsoon.The region is essentially a subtropical one and it comes under assured rainfall zone with an average rainfall of 900 mm spread in about 70 rainy days mostly received from June to September.

Study animals
The Deoni cattle are an important dual-purpose breed of cattle in India.These animals are quite popular in the tracts of former Hyderabad State which now forms the north-western part of Andhra Pradesh and adjoining districts of Karnataka and Maharashtra.Their crosses with Holstein and Jersey are very good milk yielders.Deoni cattle are hardy and well adapted to their breeding tract and constitute an important cattle genetic resource of India.They are medium-sized animal.Cows of this breed are moderately good milkers, yielding about 1135 kg in a lactation period of 300 days.Deoni bulls are good for heavy work and are particularly suitable for intensive cultivation.Traditionally, Deoni cattle are maintained under a semi-intensive system of management.This study is thus focusing on the reproductive performance of HF × Deoni crossbred cows kept at CCBP (Figures 1 and 2).

Management of animals
The management of animals at CCBP becomes identical with variation due to reason beyond control.The daily routine management activity for lactating animals starts at 8 a.m.After calving, the calves remain with their dams for about 5 to 7 h.The calves then weighed, tagged and bucket milk fed twice a day until weaning.All the calves are separated from their dam at birth and weaned at around 3 months of age.The milk recording starts after 4th day from calving.The dams remain in barn for the first five days during which they provided with green fodder, concentrate meal, and transferred to the milking herd afterwards.Cows are handmilked twice a day, early in the morning (6:00-7:00 am) and late in the afternoon (5:00-6:00 pm) after feeding concentrate mixture regularly.The cows are allowed for grazing in fallow land from 9.00 a.m. to 5.00 p.m. on a regular basis.However, in summer season (March-June) the cows are allowed for grazing from 9.00 a.m to 12.00 a.m. after that the animals are tied and stall-fed with required quantities of dry and green fodder under the shed.
All animals are routinely checked for any incident of health problem and treatments given if any abnormality exists.Additionally, animals regularly vaccinated against major diseases such as FMD, Black Leg and Haemorrhagic Septicaemia.The milking cows are washed and groomed regularly and fed individually.The project used teaser bull for regular heat detection.Upon heat detection, cows mated naturally to a bull.From conception up to 7 months of pregnancy, cows are grazed on natural pasture after which they are kept indoor and offered roughage and concentrate feed.

Sources and nature of data
Data representing 256 HF × Deoni crossbred cows from CCBP with 1485 total records of lactation over a 30 years period  were collected and organized to study the effects of period of calving, season of calving, age at first calving and parity on reproductive performance.The parameters used as indicators of reproductive performance in this study were ge at first calving (AFC), days open (DO), dry period (DP) and inter calving period (ICP).The complete year was divided into 4 seasons, according to season prevailing climatic conditions and that of the durations of study into 6 time-periods having 5 years each.The seasons  considered were winter (December to February), summer (March to May), monsoon (June to September) and post-monsoon (October to November).Six levels of age at first calving (AFC) were coded as A1 for  1000 days to A6 for  1601 days with a class interval of 150 days.The parties included L1 to L10.The four seasons namely winter (Dec-Feb), summer (Mar-May), monsoon (Jun-Sept) and post monsoon (Oct-Nov) were coded as S1, S2, S3 and S4.Cows having at least three offspring's were considered in this study (Tables 1 to 4).

Statistical analysis
System (SAS, 2002 version 9.1.3).When the analysis of variance indicated the existence of significant variation among groups, Duncan's Multiple Range Test (DMRT) was employed to test and locate means significantly differed from the rest.The following statistical model was employed to analyse the data.

Yijklm = µ + Ti +Sj +Ak +Pl + eijklm
Where, Yijklmis the Days Open (DO), Dry Period (DP) and Inter Calving Period (ICP) record of a cow calved during i th period, in j th season, at k th age of first calving, on l th parity, µ -is the population mean common to all the observations, Tiis the effect of i th timeperiod of calving (where i = 1, 2, 3, 4, 5and 6), Sjis the effect of j th season of calving (where j = 1, 2, 3 and 4), Akis the effect of k th Data were analyzed by linear models using Statistical Analysis AFC (where k = 1, 2, 3, 4, 5 and 6) groups, Plis the effect of l th parity (where l = 1, 2……………10), eijklm -Random error associated with the measurement, which is assumed to be normally, identically and independently distributed with a zero mean and common error variance i.e., IND (0.σ 2 e).

Age at first calving
Age at first calving is one of the important factors contributing to economic return.A reduction in AFC will minimize the raising costs, shorten the generation interval, and subsequently maximize the number of lactations per head.Earlier first calving increases lifetime productivity of cows.It is an important factor in determining the overall productivity of dairy cows (Singh et al., 1986).The least square means and ANOVA of AFC as affected by season and period of calving are presented in Tables 1 and 2, respectively.The overall mean of AFC in HF × Deoni crossbred cows was observed as 1198.54±8.18days.Considerably, lower

The effect of period of birth and season on age at first calving
The age at first calving was affected significantly by period of birth (P<0.01),but not by season of birth.Similar result was reported by Komatwar et al. (2010).The significant effect of period of calving on AFC could be attributed to the changes in feeding and managerial systems and environmental conditions which occurred from year to year as well as differences between years in the quantity and quality of forage availability.The nonsignificant effect of season indicates that, HF × Deoni crossbred heifers are at same level to adopt seasonal variation in the study area (Table 5).

Days open
Days open is the interval between date of calving and date of conception.It is one of the best indicator variables, which is most commonly used to measure fertility performance in dairy cattle (Arbel et al., 2001).Days open directly affect CI, which plays an important role in the profitability of dairy farms.Days open is the part of the calving interval that can be shortened by improved herd management.Long days open and consequently, prolonged CI may affect the overall economic revenues of the dairy herd.
The least square means and ANOVA of days open as affected by season, period of calving, AFC and parity are presented in Tables 6 and 7 respectively.The overall mean of days open in HF × Deoni crossbred cows was recorded as 149.15±3.87days.This result is in close agreement with the finding reported by Thombre (1996) as 151±4.9days.Considerably, shorter estimate of   113.33±7.4days was reported by Mudgal et al. (1986).However, Chauhary et al. (1989) and Thombre (1991) had reported longer days open than the present estimation.

The effect of period of calving on days open
Days open was affected by period of calving (P<0.01).
The days open was longer during 2 nd and 3 rd period while shortest days open was observed in the 4 th and 6 th periods (Table 7).Similar results were reported by Chauhary et al. (1989) and Thombre (1996).However, Basu and Ghai (1980) reported non-significant effect of period of calving on days open in different crossbred cows.

The effect of season of calving on days open
Days open was also affected significantly (P<0.05) by season of calving.The cows calved in summer season had the longest days open than the other seasons (Table 7).Similar findings were reported by Pyne et al. (1988) and Chauhary et al. (1989).However, Thombre (1996) reported non-significant effect of season of calving on days open.The variation due to season of calving on days open could be attributed to the changes in climatic conditions and feeding regimes during different seasons.

The effect of age at first calving on days open
The days open was significantly (P<0.01)affected by AFC.On the contrary, Patil (1983) has reported nonsignificant effect of AFC on DO.The maximum days open was observed from the cows which had AFC group of A 6 followed by cows which had AFC group A 5 and the minimum for those cows that had AFC group A 2 .

The effect of parity on days open
Days open was influenced significantly by parity (P<0.01).First parity cows had longer DO which was the poorest value as reproductive trait.This result is in close agreement with reports of Mudgal et al. (1986) and Chauhary et al. (1989).The variation in mean values of DO seems to be largely due to environment (management, feeding and breeding).

Dry period
The dry period is necessary for compensation of the depleted nutrients during lactation and gaining stimulation for a new lactation period.Thus, an optimum dry period is essential for maximum production of milk in subsequent lactation.A dry period, typically 40 to 60 days, between lactations believed to be required to maximize milk yield in the subsequent lactation.The least square means and ANOVA of DP as affected by season, period of calving, AFC and parity are presented in Tables 6 and 7, respectively.The overall mean of dry period in HF × Deoni crossbred cows was recorded as 126.90±1.76days.This observation was above optimum level.Thus, a considerable reduction should be achieved through improved management practices.This result is in close agreement with the finding of 125.4±4.21days reported by Jadhva et al. (1991).Considerably, shorter and longer estimates of dry period in different crossbred cows were reported by Komatwar et al. (2010) as 82.54±3.62 days, and by Deshmukh (1996) as 167.63 days, respectively.

The effect of period of calving on dry period
The dry period of HF × Deoni crossbred cows was significantly affected by period of calving (P<0.01).The dry period was longer during the 2 nd and 3 rd period of study as compared to other periods, the difference between the other periods was non-significant (Table 7).Similar results were reported by Mudgal et al. (1986) and Komatwar et al. (2010).On the contrary, Auradkar (1999) reported non-significant effect of period of calving on dry period.

The effect of season of calving on dry period
The dry period of HF × Deoni crossbred cows was significantly (P<0.01)affected by season of calving.The cows calved in summer and monsoon seasons had the longest dry period, while the cows calved in winter and post monsoon season had the shortest dry period (Table 7).Auradkar (1999) and Chenyambuga and Mseleko (2008) reported similar findings in different crossbred cows.In contrast, Mudgal et al. (1986) and Komatwar et al. (2010) reported non-significant effect of season on dry period.

The effect of parity on dry period
The dry period of HF × Deoni crossbred cows was significantly (P<0.05)affected by parity.The longest mean dry period was observed in the first lactation while; the shortest was noted in the 8 th lactation.The present finding was in agreement with reports of Mudgal et al. (1986) and Komatwar et al. (2010).In contrast, Patil (1997) reported non-significant effect of parity on dry period in different crossbred cows.

Inter calving period
The calving interval is the period between two consecutive parturitions, and ideally should be in the range of 12 to 13 months.Calving interval has a great economic importance on the lifetime milk production and productive life of dairy animals, which ultimately affects the economics of the owners.It is known that the extended calving intervals negatively affect the longevity as a productive life, because the cow with longer calving interval has fewer lactation numbers during the same period of herd life compared with cows with shorter calving intervals.
The least square means and ANOVA of ICP as affected by season, period of calving, AFC and parity are presented in Tables 6 and 7, respectively.The overall mean of calving interval in HF × Deoni crossbred cows was recorded as 422.95±2.53days.This is in close agreement with the findings reported by Auradkar (1999) and Yifat et al. (2009) as 412.07±1.46 and 418 days, respectively.Considerably, shorter estimates of calving interval were reported by Rao et al. (1984) and Chavan (2001) as 384.50±42.70 and 381.40±1.77days, respectively.In contrast, longer estimates of calving interval were reported by Deshmukh (1996) and Dahiya et al. (2003) as 511.11 and 432.42±8.19days, respectively.

The effect of period of calving on inter calving period
The calving interval of HF×Deoni crossbred cows was significantly (P<0.01)affected by period of calving.The longest calving interval was observed in the cows calved during period 1, while the shortest calving interval was found in period 6.Similar results were reported by Dahiya et al. (2003).But, Auradkar (1999) and Chavan (2001) reported non-significant effect of period of calving on calving interval in different crossbred cows.

The effect of season of calving on inter calving period
The effect of seasons of calving on the calving interval of HF×Deoni crossbred cows was not significant (P>0.05).Similar finding was reported by Deshmukh (1996).However, Auradkar (1999) and Dahiya et al. (2003) reported significant effect of season of calving on calving interval in different crossbred cows.

The effect of parity of calving on inter calving period
The calving interval of HF × Deoni crossbred cows was significantly (P<0.01)affected by parity.The longest calving interval was observed in the first lactation, while the shortest was noted in the 10 th lactation.Similar finding was reported by Nehra et al. (1987).However, Latpate (1995) and Deshmukh (1996) reported non-significant effect of parity on calving interval in different crossbred cows.A calving interval of 365 days is usually considered ideal (Khan et al., 1992).Therefore, the calving intervals, as seen in this study were somewhat longer which needs an improvement in overall management of the dairy cows.Sewalem et al. (2008) indicated that poor reproductive performance, manifested as prolonged calving intervals, which can result in reduced milk yield and increased culling rates and replacement cost.

Conclusions
The present study shows that AFC in HF × Deoni crossbred heifer is comparably longer, so it should be further reduced by proper management and selection.Moreover, days open was somewhat longer than optimal level of 80-105 days.Dry periods were also above optimum level and the calving intervals were fairly longer.Thus, a considerable reduction should be achieved in these reproductive traits through an improvement in overall management of the dairy cows.Besides, these crossbred cows were susceptible for periodical and seasonal changes on their fertility performance particularly on days open, dry period and calving interval where it will be difficult for them to thrive and maintain their reproduction potential.Therefore, additional reproductive strategies like improving environmental factors and reproductive management of cows are needed to reduce the adverse effect of periodical and

Table 1 .
Period of calving and number of crossbred cows calved.

Table 2 .
Frequency of seasonal calving and number of crossbred cows calved.

Table 3 .
Classification of crossbred cows based on AFC during the study period.

Table 4 .
Parity and number of lactation records of crossbred cows.

Table 5 .
Least square means and standard errors for age at first calving on season and period of birth.

Table 6 .
Least square means and standard errors for days open, dry period and calving interval.
a Means connected with different superscripts in a column differ significantly.

Table 7 .
Analysis of variance of means for days open, dry period and inter calving period on period, season, AFC and parity.