Sudan Academy of Sciences Journal Vol. 3 No.2, 2010

Factors Affecting some Reproductivity Indices of Butana Cows at Atbara Research Station

Badri I T. M.; Atta l M., Ibrahim 2 M. T. aI)d Gubartalla3 K. A.

ABSTRACT

In this study the reproductivity of the Butana cattle herd in Atbara Research Station during the period between the years 1949 and 1999 was evaluated. About 1338 records of 222 Butana dairy cows were analyzed to study the effect of year and season of calving and parity order on some reproductivity indices, including: age at first calving, calving interval and breeding efficiency. The data were also grouped according to sire of cows to exan1ine the sire genetic burden on cows' reproductivity. For testing the effect of years, the data were grouped according to year of calving into 5 groups (group 1: 1949 - 1959; group' 2: 1960 - 1969; group 3: 1970 - 1979; group 4: 1980 - 1289 and group 5: 1990 - 1999). For the examination of the etTect of season of calving, the data were grouped into 3 seasonal groups. Dry sumlner groups represented the cows calved during the months March, April, May and June. The wet sunlDler group included cows calved during the. months July, August, September and October. Winter group included the calvers of the lTIonths November, December, January and February. The data of this Butana herd were also grouped according to parity order of the calved cows into 10 groups. One way analysis of variance was conducted to examine the significance of effects of year of calving, season of calving and parity order on the studied traits.

] College of Natural Resources and Environmental Studies, University of Juba 1College of Veterinary Medicine and Animal Production, Sudan University of

Science and Technology 3 Atbara Research Station, Animal Resources Researches Corporation

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Heritability \vas estinlated by paternal half sib analysis. The age at· first calving, calving interval and breeding efficiency of Butana COV/S

in this study ·were 3.7 ± 0.81 years, 13.2 2.5 1110nths and 79.4 ±12.27 0/0, respectively.· The result docu111cnted significant effect of year of calving on all of the reproductive traits measured" while season of calving had significant effect only on the breeding efficiency. The heritability estinlate of the age at first calving, calving interval and breeding efficie11cy were 0.60 0.07, 0 3 ± 0.05 and 0.18 0.04, respectively. It can be concluded that the reproductivity of Butana CO\VS at Atbara Research station was relatively· high and was significantly affected by nlanagerial systelTIS that changed with years and the environnlental variations of calving season and not by age of Co\vs.

,

INTRODUCTION

Reproduction is one of the cardinal characteristics of all living organisnls. It is the process that results in the formation of new individuals of the same kind, though slight genetic structural and physiological variation may appear. Reproduction is an indispensable phenoluenon for preserving the species and it is necessary to replace the losses that occur due to mortality. The continued production of any livestock commodity depends on many genetic. and non-genetic factors that exert effects of variable extents on reproduction. Age at first calving, calving interval and breeding efficiency are very essential reproductive indices that measure females' fertility. First calving marks the begil}lling of a cow's productive life. Under controlled breeding system, heifers are usually mated when they are mature enough to withstand the stress of parturition and lactation. This increases the likelihood of early conception after parturition. Jordan (2006) noted that in traditional production systems breeding was often uncontrolled and heifers are bred at first opportunity, and this resulted

. in longer subsequent calving intervals.

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Regular calving of dairy cows every 12- 13 lTIonths is economically desirable for profitable production (Bath et al .. 1985). Calving interval has been reported by Jordan (2006) as the best index of herd's reproductive efficiency. He also stated that calving interval consists of three periods: gestation, postpartum anoestrus (from calving to the first estrus) and the service period (frol11 /flrst postpartuITI estrus to successful conception). The postpmiun1 anoestrus and service periods ITIay be collectively named the days open period and it is the part of calving interval that can be shortened by improved herd lTIanageITIent (Peters, 1984). He also noted that the days open period should not exceed 80 - 85 days if a calving interval of about 12 months is to be achieved and this requires fe-establishment of ovarian activity soon after calving and high conception rate. Bearden and Fuquay (1986) explained that an average breeding efficiency of less than 100 % indicates that reproduction does not occur at a'regular interval of 365 days in the herd studied. Bhatnagar and Shanna (1970) reported 84 % breeding efficiency for Sahi\val cows in India. While, Goshu (2005) reported that the overall breeding efficiency of Friesian- Boran crossbred CO\VS in Ethiopia was 66.3 0/0. He added that this lo\ver efficiency indicated that the general herd rr~anagement was not Opti1TIUll1 for the genetic expressions of the different breed groups. He also noted that the level of abortion rates and length of calving intervals might have contributed to the low breeding efficiency of crossbred cows. Cows calved in the Sh01i· rainy season had high breeding efficiency (Go shu and Hegde, 2003). They stated that shQrtage of feeds in the dry season and the incidence of parasites and infectious diseases in long rainy season might have contributed to the lower breeding efficiency of cows in these seasons. Goshu (2005) noted that breeding efficiency in the e~rly parities was poor and he attributed this to delayed resumption of ovarian activity after calving. Moreover, the lo\v breeding efficiency .of young animals Inay be due to the fact that conception is usually influenced by the further need of nutrients for. the continued growth and lactation. The inlproved br~eding efficieru;;y

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of cows after the fourth parity may be due to the culling out of repeated breeding COWS.

Evaluation of the relative irnpacts of heredity and environment on the reproduction and production traits of animals is greatly aided by estilnates of heritability and genetic relationships. According to Cameron (1997), heritability is de tined as the proportion of the total phenotypic variance attributed to the additive genetic variance. A higher heritability indicates that a substantial proportion of phenotypic variance is due to additive genetic variation. Non additive genetic factors (environmental factors) Inake a relatively larger contribution to phenotypic when the heritability is low. Falconer (1986) stated that heritability is a measure of the phenotypic differences behveen parents that can be passed on to their off-spring. As regards the reproductive traits, Werre and Brinks (1986) concluded that reproductive traits have la~ger environmental variance and lo\.v additive genetic variance. This shovls \.vhy the female reproductive traits are slightly heritable. Santoro et al. (2005) classified heritability into: low heritability that ranged between 0.0-0.20 as for most of the reproductive traits, medium heritability that ranged between 0.21-0AO, as for most of the productive traits 'and high heritability and this is more than OAO, as for the body measurements. ", This study aims to investigate the effects of year and season of calving and cows' parity order on the reproduction potential of Butana cattle raised in Atbara research station. The study further aims at. the evaluation of the genetic impact of the studied reproductive traits.

MATERIALS AND ME,{HODS

The data of age at first calving (in years) and breeding efficiency(%) of 222 cows and 1338 records of calving intervals (in months) of the Salne cows were used in this study .. The breeding efficiency was calculated according to Goshu (2005): breeding efficiency (BE) = lOO*365*(N-l)/D, where N is the total number births given by the ~o\v and D is nUlnber of days fron1 the first tn the last parturitions.

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This data \vas obtained frolll Atbara Research Station records and it covered the period froll1 1949 to ] 999.

Animals in the station \vere allowed.· to graze on Sorgh llln

hie%r (Abu-70), Cyamopsi,,>' tetragnoloba (Guar), Afedicago sativa (Berseem) and Sorghuin slldanensis (Graw,ia). In addition to grazing, the ll1ilking cows were fed on a concentrate/ diet. The ne\v bODl calves were fed on colostrum for 7 days and then on fresh 1nilk at 2.7 kg of 11lilk per calf, approximately, to an age of one 1110nth. Only natural Inating was practised. The cows were allowed to be served after two months post calving, while heifers were usually allowed at first estnls signs appearance. Breeding bulls were selected fronl progenies of the highest yielding dams in the herd. To study the effect of years, the data were categorized into five period groups according to the years of calving. Each period group extended for ten years (group 1: 1949 - 1959; group 2: 1960 - 1969; group 3: 1970 1979; group 4: 1980- 1989 and group 5: 1990 - 1999). For the evaluation of the effect of season of calving the data were grouped into three groups; dry SUlnlner (March-June), wet summer (July­October) and winter (November- February). The data was also classrfied according to cows' parity order into ten parity groups (1 st

10th). The data was also grouped according to sire of cows to exanline

the sire genetic burden on their perfoDllance. One way analysis of variance was conducted using Statistica computer software (StatSoft, 2001) to examine the significance of effects of year of calving, season of calving and parity order on the studied traits. A 2-way analysis of variance was used to examine the significance of effect of year x season of calving interactions on the studied traits. DtIDCan's mUltiple range test was used to test the significance of differences between means. Heritability was estiInated by paternal half sib analysis as described by Becker (1975).

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Results A.nd Discussion

The age at first calving observed in the present study (Table, 1) was 3.7 0.81 years. This result is comparable to the 45.09 3.56111onths

Table I. Description of some Reproductive Traits of Butana Cows Raised in Atbara Research Station During the Period 1949- 1999

Traits Age at first calving (years)

Breeding efficiency (%) Calving interval (lTIonths)

No = Number of observations h2

= heritability

No 222

222 1338

Mean±SD b2

3.7±0.81 0.60 ± 0.07

79.4 ± 12.27 0.18 ± 0.04 13.2 ± 2.50 0.23 + 0.05

reported by Musa (2001) for the SaIne breed. Ageeb and Hiller (2001) fOillld that Butana cows calved for the first tilne at 4.08 ±0.48 years. The present value is higher than the 946.3 91.6 days that were reported by Abu-Eissa. and Atta (2004) for the Friesian x Kenana crossbred cows and 943 ± 7.0 days repolied by Godera et al. (1990) for Friesian x Haryana crossbreds. Nilfqrooshan and Edriss (2004) reported 21 months as age at first calving for pure Holstein. The high value of age at first calving of Butana cows reported in the present study compared to the pure European breeds and their crosses could be attributed to the fact that European breeds approach faster weight of sexual maturity (EL-Habeeb, ·1991). This observation was consistent with that repo;ted by Lawrence and Fowler (1997), who stated that the animal body weight is more determinant to the sexual maturity than its age. Age at first calving in the present study was significantly (P < 0.05) affected by the year of calving (Table, 2).

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Table 2. Effect of Years of Calving on some Reproductive Traits of Butana Cows

Tn~its No I Age at fil'st Breeding No Calving calving (yeal's) efficiency (%) interval

! (months)

Pedod

89.09'1 J45 13.64b

1949·- 1959 4.35'\) 79.84b 666 12.57c

1960 - 1969 21 106·

3.52d

I 1970 - 1979 61 ,:".;. 74.03 c 318 13.5S b

~1980 - 1989 3.47d

21 77.65b . 124 13.4 7b l

I 3.90c

11990'=l~-13 ---:-. 81.68b -85 15.02a

I I 4.76:1

~'----~~--r 0.04 0.82 - 0.17 ! ,.)~

!---'--i~:~-:-;i:-~; f ! _... . !

. ~. "J~ ;.~ ... '"'>T 1'''',0,. . S* S* S* I Sl",.1dk.an",,-, ~~~_.~~ ... -::~,,. .......... _____ -L

No ::;;"rrumlH::r of observation. n l'~ 'S' l. -l f' :',f~ ;:= ". tan(~aru, error 0 mean. S"O;:: = ~';O"';fi""a'nt (1)<0 05) .. ~ U.iA,t?JtJl.~t. . .::.'''-1'- 1. : ~ .... '" .. ..

a,b and c: !neans in the sanle column with different superscripts are sign,ificantly (p<OJJ5) different.

J-Io\ve'ver, th.is (::fIect showed unstable trend. Cows of the decade (1990 -: 1999 years group) gave their first calves at the eldest age; followed by the GO'W§ of the first decade (1949 - 1959 years group) vvhereas the cows calved during the decades 1960 .- 1969 and 1970 - 1970 gave their first calves at the earliest age. The effect of year of calving on the age at first (~Hlvin,g \vas. also reported by' "h:..geeb and I-liller (2001) and

Sudan Academy of S~lences Journal Vot:3 No.2. 2010

Saeed et al. (l987) for the Sudanese indigenous dairy cattle~ wIiranda ef af. (1982) for Brazilian indigenous breeds and Sabino et al. <. 1981) for dairy cows in Venezuela. However, only the tonner anthors observed a similar trend for the effect of year. Se~ts\)n 0 f .. ~:-.~ ving (Ld not show significant effects on cows' age at tirst cal ving Cfable, 3).

Table 3. Effect of Season of Calving on SOUle Rellfodudive TI~ait'i of Butana Cows

No = number of observation. SE = Standard error of Inean. S* = significant (p< 0,05). NS = Not Significance. a, b: means in the same column with different superscripts are significantly (p<O.05) different.

The effects of interactions of year x season of calving on the age at first calving were significant (Table, 5). The cO"ws of the three season groups of the decade (i 990 - 1999 years) and the dry summer and winter seasons groups of the decade (1949 -- 1959 years) calved for the first thne at similar ages. They were significantly latter than the ages of the cows of the season groups of the other examined decades.

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Significant effect of years x season of calving interaction on cows age at first calving was also reported by I'v1usa (2001), EI-Habeeb (1991), Saeed et al. (1987) and Morde and Akinokun (1986). Musa (2001) and Saeed et al. (1987) observed trends of this effect similar to that of the present study. The Inean of calving interval of Butanac,attle in the current study "was ] 3.2 ± 2.50 months (Table, 1). This/ result is comparable to the findings of Musa (2001)(382.28 ±8.30 days), El-t-Iabeeb (1991) (373.94 + 74.94 days), for Butana cattle, and Ishag (2000)(12.9 ± 0.1 lTIonths) and Ageeb and Hiller (1991) (14.2 months) for Friesian x

Kenana crossbred d~iry cows in the Sudan. On the other hand, the present result was markedly lower .than that reported by Saeed et al. (1987) (485 ± 5.1 days) for Kenana cows. Analysis of variance of the CUlTent data showed that the year of calving had significant (p<0.05) effect on calving interval (Table, 2). Cows calved during the decade (1990 -'-: 1999 years) showed significantly longer calving interval than that of cows calved during the other exmnined decades. Significant effect of year of calving on calving interval was also reported by Ageeb and }Iiller (1991), Saeed et al. (1987) for the Sudanese indigenous dairy breeds, Eid (2001) for the imported and homebred Friesian cattle in the Sudan. Silnilar result \l'I!'as also reported by Karan and Joshi (1990) for Karan - Swiss cattle. However, Ageeb and Hiller (1991) and Saeed et a!. (1987) observed a trend opposite to that of the present study (i. e. calving interval decreased 'with year progression). Season of calving (Table, 3) and cows' parity order (Table, 4) had no effect on calving interval. The year x season of calving interactions had significant (p<O.05) effect on calving interval of Butana dairy cows (Table, 5) at Atbara Research Station. This result is consistent with that reported by EI-Habeeb (1991) for Butana and Kenana dairy breeds and Fadlel- Iv10ula (1994) for the Sudanese crossbred dairy cows. But the result in this study disagreed with the finding of Musa (2001), who reported that year x season of calving interactions had no effect on calving interval of Butana CO\VS at Atban! Research Station.

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Such disagreenlent Inight be due to the differences in th.e nnn1ber of years in each experirnental year group (about to years/g~'oup iril the present study).

Table 4. Effel~t of cows' Parity OrdeR' on some Rcpn)ducHveTraits oj' Butana CO\"s

No :;:;-; 11un1ber of obserVation. SE ;=~ Standard error/(;(~ean.

. i

S * :-:= significant (p:'~O.05)~ NS = l~ot Signific.iant a~ b : rneans in the samecolurran with different superscripts are s.ignifill~antly (p<OoO:S) different

92

I

i

Sudan Ac.:~d!!'lm,y· of Sciences Journal Vol. 3 No.2, 2010 ............ "-.. -.,,~~----------------.------------

Table 5. Effect of Yeal" x Season Interaction on some Reproductive Traits of Butana Cows . Age at first ; c3hino (Y(:'a1's)

b •

l ! !

I :.=.:~.::..:...~._._:N_, ___ . ___ -+ ___ . __ .. _________ -+-_ .. __ . ___ . ___ .-.--+-----_t_----.----:c-----......l

_11_ln._e. __ r. ____ . __ ~_.--.. ---.---~-.--.-)-~·.-0--6.ra ___ ~---1. __ ---8--8-.(-)-9-----r--2-6-__+---~:·~~:_---li arl X )Vet 4 3.7 9 i .25 30 1 L.L9

nmer - ... --..:....--~_+-----.-t_--.. --_=_---.__+-------.-+--.. --_t_-----~----I

'12 88.47 89 13.65 I I

dry 38 14 241 1 ') 6'" b -.. --.. -...1 _. ?)

1,.}~-'-n_u.;.::.:::r ____ --+_ .. _ ... __ .. _ ... _ .. _+---.. -------__.::__---_+_--________ +-____ + ____ ~--_--~ ar2 X wet 27 79.34 159 12.6<yJ!

I -orner 1 -'-----'----'---"'\-"---4-2-·,---+------·---3---.:.-----+---·---R-0-.-7-8·--·-+-------t--------,::---.------.]

dry 'tmer 11"'3 X "t,+-'et nner

ter

!1r.j. X ,Yet uuer

ter dry

lrs X ,vet lmer

ter

'el line-ant

34 1-....

8 ., -, .

19 3

10 ., .')

5

74.06

73.57

74.92

79 .. 62

1"

79.08 28 15

84.44 ]9 14.81 a

82.13 30 14.97:1

1.60 0.332 NS S*

t'· 'J ;J , . .,

Sudan Academy of Sciences Journal Vol. 3 No.2, 2010

. No = Number of observations Year1= (1949 - 1959), Year2 = (1960 - 1969), Year3 = (1970 - 1979), Year4 = (1980 - 1989), Years = (1990 - 1999) Dry summer = (March- June), Wet summer = (July - October), Winter = (November February) S* = Significant (p<0.05) NS = Not significant a, band c: means with the same collunn with different superscripts are significantly (p<O.05) different.

The percentage of breeding efficiency of Butana cows in the current study was 79.4 ± 12.27% (Table, 1). This result is lower than 95% stated by Kiwuwa et al. (1983) for various Friesian inheritance cows at Asella Station in Ethiopia and than 84 % reported by Bhatnagar and SharaIna (1970) for Sahiwal cows in India. The current result is higher than 72.2 16.5 % reported by Ageeb and Hiller (2001) for the Sudanese indigenous dairy cows and 66.3% reported by Goshu (2005) for Friesian x Boran crossbred cows in Ethiopia. The breeding efficiency of the present Butana herd \vas significantly (p<O.05) affected by the year of calving (Table 2), season of calving (Table 3) and parity order (Table, 4). The first and last decades' groups had similar breeding efficier~:cy percentages and they were significantly hig~er than those of the other decades which were similar. Similar effect of year of calving was reported by Goshu (2005) for Friesian x Baran crossbred dairy CO\Vs in Ethiopia. The winter season (November - February) calvers in the present study showed the highest breeding efficiency value than the other seasons' calvers. Generally,. the. seasonal decline in breeding efficiency could be due to the variability of rainfall and deterioration of management in feed, health and reproduction (Go shu, 2005). Estimation of heritability of age at first calving in the current study (Table, 1) was high (0.60 ± 0.07). Heritability is not constant for the same trait and may show wide variation, depending on the herd in which it is measured (Falconer, 1986). There are many studies that

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,ho\ved the heritability of age at first calving was low. Gumani et al. ,1.976) reported that the heritability of the age at first calving was ).114 ± 0.139 for Sahi\va1 CO\vs. Moore et al. (1990) reported that the lcritabHity of the age at first calving was 0.09 and:O.039 for Ayrshire lnd Holstein, cows, respectively., Dong and Van Vleck (1989) ~stilnated heritability as O. 15 for age at first calving. A.ccording to Santoro et al. (2005), heritabilityofcalving interval in :he present study was 1110derate (0.23± 0.05) (Table, 1). The value of the present study was higher than the 0.023 0.029 that reported by EI-Habeeb (1991) for the sanle breed, and than the 0.09 ± 0.09, 0.05 ± J.OS and 0.14 0.03 that reported by Fengaly (1980) for Kenana cows at Nisheshiba and UlTI- Baneih research stations and Butana cows, at Atbara station, respectively. However, the present result was 00nlparable to 0.24 ± 0.07 that was reported by Singh et aI. (1993) for the same trait in Sahi\\ral and its crosses with Jersey and Red Dance. Lower results were also observed by Rao and Nagarcenkar (1992) (0.078) and by Wollny et al. (1998) (O.04± 0.03). The reproductive efficiency (breeding efficienQY) had low heritability estilTIate (O.18± 0.4) in the present study (Table, 1). This finding is in agreement with that reported by Benya et af. (1976) who reported that the reproductive efficiency in dairy cattle has very low heritability (0.05). This low heritability suggests that selection would not be effective in ilnproving reproductive efficiency. Wilcox et af. (1971) stated that not more than 5% of the total variation in this trait was associated with additive genetic variation. Contradictory observation was reported by Hoeschele (1991). He noted that for the breeding efficiency trait the unexpected variance is 80 to 90 % of total variation, and this leaves about 10 - 12 % due to identifiable environmental factors. Macmillan (1999) reported that the effects of environmental factors which depress fertility, e.g. high temperature and hunlidity, can be reduced by altering housing, feeding and roofing conditions. He also reported that the beneficial effects of improved feeding conversion effiCiency and animal health on reproduction were associated with iUlprOVetnents in dairy production. Therefore, costs

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providing a less stressful environnlent should take account of increased returns frolll reproduction. The study concluded that the relatively young age at first calving,· . short calving interval and high breeding eHiciency of Butana CO\VS in the present study indicate their high reproductivity. The significant effect of year of calving on these indices indicated the variations on the managelnent systems practised during these periods, whereas the effect of season of calving Inight be due to variation in the clinlatic paranleters (telnperature, light and rainfall) of the seasons tested. These observations \vere consistent \vith the low heritability estilnates obtained, indicating the large burden of the environment and management systems practices on thenl.

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