Evaluation of Sires Using Different Sire Evaluation Methods on the Basis of First Lactation Traits in Sahiwal Cattle

The records of 1367 crossbred cattle sired by 112 bulls were analysed to estimate breeding values and to compare various methods of sire evaluation viz. BLUP, LSM and sire evaluation methods on the basis of age at first calving, first service period, first lactation period, first dry period, and first calving interval. The average breeding value for FLMY. FLL, AFC, FCI, and FDP were estimated as 1711.63 kg, 320.38 days, 1299.54 days, 524.25 days and 207.60 days by method, 1941.16 kg, 321.60 days, 1287.12 days, 514.86 days and 195.57 days by LSM method and 1890.06 kg, 313.70 days, 1281.25 days, 508.56 days and 194.46 days by BLUP method. The accuracy, efficiency and stability of EBV’s of sires for the first lactation and lifetime traits were compared by different methods to judge their effectiveness. The estimated breeding values of sires for all the first lactation traits by , LSM and BLUP revealed that EBV’s of sires estimated by least squares method showed smaller genetic variation in comparison to and BLUP methods. The LSM was adjudged as the most efficient method of sire evaluation. The LSM had minimum error variance for most of the first lactation traits and considered to be more superior over other two methods i.e., and BLUP. The product moment correlations among the estimated breeding value of sires for first lactation traits by , LSM and BLUP methods ranged from medium to very high and significant (P<0.01) in all the three methods of sire evaluation. The rank correlations among the breeding value of sires estimated based on first lactation traits were medium to high and significant (P<0.01). The results indicated that least square method (LSM) had the lower error sum of square for all the first lactation traits and least square method (LSM) is relatively more accurate as compared to best linear unbiased prediction (BLUP) method but not overall. The LSM had higher R2 value for the first lactation traits as 40.50% (FLMY), 18.17% (FLL), 23.94% (FCI), 24.59% (FDP) and 48.47% (AFC) than the BLUP method. The estimated R2 values are less which indicates that both methods are less suitable for present data. Therefore as for as stability is concerned among the methods of sire evaluation, the LSM method was most stable being its CV (%) which is closest to the CV (%) of unadjusted data. The rank correlations obtained were highest and statistically significant (P<0.01) and ranged from 0.74 ( and BLUP) to 0.88 ( and LSM). The highest rank correlations among the breeding values estimated from different methods revealed that rankings of sires were similar to the extent of 74 to 88 per cent from these methods of sire evaluation.


Introduction
Indigenous cattle are particularly suited to the climate and environment of their respective breeding tract.They are endowed with qualities of heat tolerance, resistance to diseases and ability to thrive under extreme climatic stress and lesser than optimal nutrition.The performance of Sahiwal cattle is remarkable in hot climate and has been recognized worldwide as one of the best milch breeds [1].Due to its resistance against various diseases and heat tolerance properties, many countries have imported this breed from Pakistan and India for the production of synthetic breeds of cattle.At present, the selection criteria for young males for future breeding are based on physical appraisal traits of the young bulls and the milk production performance of their dam.These attributes may not adequately represent the real potential of the sire for milk production.Therefore, selection of sire in the future should base on breeding value of the sire.
There are several methods of sire evaluation with a wide range of complexity starting from very simple (simple daughter average) to highly complicated (REML) method.Different methodologies like contemporary comparison, contemporary daughter average index, least squares (LSM) technique and simple regressed least squares technique (SRLS) could be used to evaluate sires for a single trait i.e., milk yield.Henderson opined that analysis of variance and covariance may give biased components of variance from selected population; whereas restricted maximum likelihood (REML) estimate can give bias free estimators [2].Simultaneous attention to reproductive traits in addition to milk production is expected to bring about overall improvement in the index value of a sire.So, multi trait criteria of sire evaluation using advance statistical technique like derivative free restricted maximum likelihood (DFREML) and best linear unbiased prediction (BLUP) would be expected to enhance the accuracy of selection of the bulls.

Journal of V Journal of Veterinary Science & eterinary Science & T Technology echnology
One has to look in the efficiency of these methods with practical applicability to the local conditions.This paper reports breeding value of Sahiwal sires using 3 sire evaluation methods and compares the methods in terms of efficiency, accuracy and stability of the different sire evaluation methods by within sire variance (error variance), Relative efficiency (RE), the coefficients of determination and coefficient of variation of different methods.

Materials and Methods
The data for the present investigation were collected over a period of 71 years (1944-2014) from pedigree sheets of 1367 Sahiwal cows born to 112 sires maintained at Government Livestock Farm, Chakganjaria, Lucknow (UP).Only the sires having records on at least 3 daughters were included in the present study.The total duration of the present study was divided into 8 periods.Out of 8 periods 7 are of nine years each and 8th period of 8 years only.Each year was divided into three seasons namely winter (November-February), summer (March-June) and Rainy (July-October).In order to classify the data for different periods and seasons, year and season of calving was considered for all the traits.The traits considered in the present study were age at first calving, first lactation length, first dry period, first calving interval, and first service period.

Statistical analysis
As the data in the present study were non-orthogonal in nature with unequal subclass numbers, they were subjected to least squares analysis of variance without interactions using different models to examine the effect of genetic as well as non-genetic factors on various first lactation traits as per standard procedures of Harvey [3].The model was based on the assumption that different components fitting in the model were linear, independent and additive.While sire was treated as random effect, the other genetic and non-genetic factors (genetic group, season and period) were taken as fixed effects in the model.The main objective of sire evaluation is to obtain an accurate and unbiased estimate of breeding value of bulls and ranking them on the basis of performance of their daughters so as to enable the breeders to choose the best bull for subsequent improvement of the herd.Many sire evaluation methods based on performance of adequate number of progeny recorded have been proposed.The following three methods of sire evolution were used to estimate the breeding values of sires.

Simple Daughters Average
Sires were evaluated by Simple Daughter's Average as proposed by Edward [4].The breeding values of sires were computed as follows I = Where, is the average milk yield of all daughters of a sire.

Least Squares Method (LSM)
The Least Squares Method was used to estimate the breeding value of sires, using the following statistical model [3].

Yij=μ+Si+eij
Where, Yij=jth dependent single trait of the daughter of ith sire μ=population mean Si=effect of ith sire eij=random error assumed to be normally and independently distributed with mean zero and variance σ 2 i.e., NID (0,σe 2 ).
Best Linear Unbiased Prediction: BLUP F90 and related programs were developed in the lab of Misztal et al. with the purpose of providing comprehensive computing capabilities to problems related to mixed models in animal breeding [5].Best Linear Unbiased Prediction (BLUP) method Under BLUP method, the sire effects were obtained by using single trait model.For this purpose the LS estimates of variance components from the corresponding model were used.The BLUP evaluations were based on an animal model which utilized information from all the known relationships.The BLUP evaluations were obtained under single trait animal model.
The effectiveness of different sire evaluation methods was judged by within sire variance (error variance).The method giving lowest error variance had higher efficiency and was most appropriate.The efficiency was measured by the following equation.

Efficiency = 1 Error variance
Relative efficiency (RE) of method II with respect to method I (most efficient method) was calculated by the following equation.

RE % =
Error variance of method I Error variance of method II ×100 The coefficients of determination (R 2 -Value) of different methods were estimated for judging the accuracy of sire evaluation method.
The coefficient of variation (CV%) of traits under study from different models of sire evaluation were estimated for judging the stability of sire evaluation methods.The Spearman's rank correlation between breeding values of sires derived by various methods was used to judge the effectiveness of different methods.The rank correlation was estimated as per Steel and Torrie [6].
Where, r=Rank correlation coefficient n=number of sires under evaluation di=difference of rank between paired items under two methods The significance of rank correlation was tested by t-test as given below: 2 ) It was compared with t-table value with (n-2) degree of freedom.

Results and Discussion
The different descriptive statistics such as mean, minimum and maximum breeding value and range are presented in Table 1

Simple daughters average
The minimum and maximum breeding values of first lactation milk yield were 974.00 kg and 4061.00 kg respectively.Forty one out of 112 sires (36.61%) had breeding value above the average, while 71 sires (63.39%) had their breeding value below the average breeding value.The top ranking sires had very high genetic superiority over the overall average, whereas bottom ranking sires had 43.10% low breeding value than overall average breeding value (Table 1).
The minimum and maximum breeding values of first lactation period were 243.00 and 419.00 days respectively.56 out of 112 sires (50%) had breeding value above the average, while 56 sires (50%) had breeding value below the average breeding value.The top ranking sires had 24.14% higher genetic superiority over the overall average, whereas bottom ranking sires had 30.78% low breeding value than overall average breeding value (Table 1).
The minimum and maximum breeding values of age at first calving were 904.00 and 1950.00 days respectively.56 out of 112 sires (50%) had breeding value above the average, while 56 sires (50%) had breeding value below the average breeding value.The top ranking sires had 30.44% higher genetic superiority over the overall average, whereas below average ranking sires had 50.05% low breeding value than overall average breeding value.
The minimum and maximum breeding values for first calving interval were 380.00 and 870.00 days respectively.52 out of 112 sires (46.43%) had breeding value above the average, while 60 sires (53.57%) had breeding value below the average breeding value.The top ranking sires had 27.52% higher genetic superiority over the overall average, whereas below average ranking sires had 65.95% low breeding value than overall average breeding value.
The minimum and maximum breeding values for first dry period were 92.00 and 510.00 days respectively.52 out of 112 sires (46.43%) had breeding value above the average, while 60 sires (53.57%) had breeding value below the average breeding value (Table 1).The top ranking sires had 55.68% higher genetic superiority over the overall average, whereas below average ranking sires had lower genetic worth than overall average breeding value.

Least Squares Method (LSM)
The minimum and maximum breeding values of first lactation milk yield were 906.92 kg and 3377.00 kg respectively.20 out of 112 sires (17.86%) had breeding value above the average, while 92 sires (82.14%) had breeding value below the average breeding value.The top ranking sires had very high genetic superiority (73.96%) over the overall average, whereas below average ranking sires had 68.73% low breeding value than overall average breeding value (Table 1).
The minimum and maximum breeding values for first lactation length were 219.00 and 397.77days respectively.44 out of 112 sires (39.29%) had breeding value above the average, while 68 sires (60.71%) had breeding value below the average breeding value.The top ranking sires had 23.68% higher genetic superiority over the overall average, whereas below average ranking sires had 32.25% low breeding value than overall average breeding value.
The minimum and maximum breeding values of age at first calving were 813.96 and 1722.39 days respectively.54 out of 112 sires (48.21%) had breeding value above the average, while 58 sires (51.79%) had breeding value below the average breeding value.The top ranking sires had 36.76%higher genetic superiority over the overall average, whereas below average ranking sires had 33.82% low breeding value than overall average breeding value (Table 1).
The minimum and maximum breeding values for first calving interval were 265.11 and 741.57days respectively.42 out of 112 sires (37.50%) had breeding value above the average, while 70 sires (62.50%) had breeding value below the average breeding value.The top ranking sires had 48.51% higher genetic superiority over the overall average, whereas below average ranking sires had 44.03% low breeding value than overall average breeding value.
The minimum and maximum breeding values for first dry period were 24.24 and 360.63 days respectively.49 out of 112 sires (43.75%) had breeding value above the average, while 63 sires (56.25%) had breeding value below the average breeding value (Table 1).The top ranking sires had 87.61% higher genetic superiority over the overall average, whereas below average ranking sires had 84.80% low breeding value than overall average breeding value.Deulkar and Kothekar reported estimated breeding value of Sahiwal sires for FLMY ranged from 517.46 to 1859.64 kg using least square method of sire evaluation [7].Banik and Gandhi reported average breeding value of Sahiwal sires for first lactation milk yield (FLMY) as 1502.27kg and it ranged from 830.41 kg to 2247.90 kg [8].Dongre and Gandhi reported overall breeding value of 1880.85 kg using least square method [9].Gandhi and Gurnani [10] Singh [11] observed higher estimate of breeding value for this trait using least squares method of sire evaluation.

Best Linear Unbiased Prediction (BLUP)
The minimum and maximum breeding values of first lactation milk yield were 1153.95 and 2560.29 kg respectively.38 out of 112 sires (33.93%) had breeding value above the average, while 74 sires (66.07%) had breeding value below the average breeding value.The top ranking sires had 35.46% genetic superiority over the overall average, whereas below average ranking sires had 38.95% low breeding value than overall average breeding value (Table 1).
The minimum and maximum breeding values of first lactation period were 217.90 and 390.89 days respectively.54 out of 112 sires (48.21%) had breeding value above the average, while 58 sires (51.79%) had breeding value below the average breeding value.The top ranking sires had 24.61% genetic superiority over the overall average, whereas below average ranking sires had 15.31% low breeding value than overall average breeding value.
The minimum and maximum breeding values of age at first calving were 1007.41 and 1546.38 days respectively.55 out of 112 sires (49.11%) had breeding value above the average, while 57 sires (50.89%) had breeding value below the average breeding value.The top ranking sires had 21.37% genetic superiority over the overall average, whereas below average ranking sires had 20.69% low breeding value than overall average breeding value (Table 1).
The minimum and maximum breeding values for first calving interval were 365.31 and 658.35 days respectively.52 out of 112 sires (46.43%) had breeding value above the average, while 60 sires (53.57%) had breeding value below the average breeding value.The top ranking sires had 28.17% genetic superiority over the overall average, whereas bottom ranking sires had 29.45% low breeding value than overall average breeding value (Table 1).
The minimum and maximum breeding values for first dry period were 89.96 and 303.40 days respectively.Out of 112 sires 47 (41.96%) had breeding value above the average, while 65 sires (58.04%) had breeding value below the average breeding value.The top ranking sires had 53.74% genetic superiority over the overall average, whereas below average ranking sires had 56.02% low breeding value than overall average breeding value (Table 1).Deulkar and Kothekar reported estimated breeding value of Sahiwal sires for FLMY ranged from 1262.90 to 1543.65 kg using BLUP method of sire evaluation [7].Banik and Gandhi [8] Kumar and Gandhi [11] using LSM reported lower estimate (1463.33,1520.72 and 1522.53 kg, respectively) than the present estimate of breeding value in Sahiwal sires.Kumar and Gandhi [11] using BLUP method reported 1581.80 kg breeding value for FLMY.Dongre and Gandhi [9] using LSM reported average estimated breeding value of 1869.91 kg which range from 928.33-2641.06kg and 28 out of 51 sires (54.90%) had breeding value above the average, while 23 sires (45.10%) had breeding value below the average breeding value.

Comparison of sire evaluation methods by error sum of square
The error sums of square from both of the above methods of sire evaluation studied along with their relative efficiencies were summarized in Table 2.The results indicated that least square method (LSM) had the lower error sum of square for all the first lactation traits as 743822164.00for FLMY, 7920813.03 for FLL, 22643510.79for FCI, 16766860.45for FDP and 51109094.30for AFC.Whereas, in best linear unbiased prediction (BLUP) method the error sum of squares for these traits were 771433516.00(FLMY), 8143844.23 (FLL), 23664944.85(FCI), 17432184.07(FDP) and 56228513.62(AFC).The finding revealed that the least square method (LSM) was adjudged most efficient method over best linear unbiased prediction (BLUP) method.The relative efficiency of BLUP over LSM was 96.42% for FLMY, 97.26% for FLL, 95.68% for FCI, 96.18% for FDP and 90.90% for AFC.These results depicted that both the methods have estimated breeding value with fairly high accuracy as relative efficiencies of BLUP for all the first lactation traits with respect of LSM was higher than 90%.Various workers had compared different methods of sire evaluation on the basis of relative efficiency and differed in their conclusion and advocated [12][13][14] that BLUP was one of the most efficient methods of sire evaluation compared to LSM.However, similar to present findings, Sahana and Gurnani [15], Mukherjee [16] and Banik and Gandhi [8] reported that LSM is most efficient over the BLUP method of sire evaluation.While Dubey et al. [12] and Bajeetha and Singh [13] also reported BLUP as best procedure in comparison to other procedures of sire evaluation.

Coefficient of determination (R 2 )
The coefficient of determination (R 2 ) is of fitting the different models to judge the accuracy of sire evaluation methods for the first lactation traits (Table 2).The higher the R 2 value, the higher was the accuracy of fitting the model.It was found that LSM had higher R 2 value for the first lactation traits as 40.50% (FLMY), 18.17% (FLL), 23.94% (FCI), 24.59% (FDP) and 48.47% (AFC) followed by BLUP where R 2 values for these traits were 38.30% (FLMY), 15.90% (FLL), 20.50% (FCI), 21.60% (FDP) and 43.30% (AFC).These finding clearly indicated that when R 2 -value was used as criterion to judge the effectiveness of sire evaluation method LSM was found to be fittest over the BLUP method of sire evaluation, but the accuracy of BLUP was much close to LSM.
Similar to these findings, Gandhi and Gurnani [10] compared accuracy of LSM and BLUP method using R 2 -value and revealed that LSM was most accurate.On the other hand, Banik (2004) reported highest R 2 -value of BLUP (24.54%) and by LSM (11.07%) for FLMY.

Table 1 :
. The average breeding values of 112 sires evaluated by D, LSM and BLUP sire evaluation methods on the basis of first lactation milk yield, first lactation period, age at first calving, first calving interval and first dry period.The average breeding value for FLMY.FLL, AFC, FCI and FDP were estimated as 1711.63 kg, 320.38 days, 1299.54 days, 524.25 days and 207.60 days by D method, 1941.16kg, 321.60 days, 1287.12 days, 514.86 days and 195.57days by LSM method and 1890.06 kg, 313.70 days, 12891.25 days, 508.56 days and 194.46 days by BLUP method (Table 1).Average Breeding Value of Sahiwal Sires for First Lactation Traits by Different Methods.

Table 2 :
Singh J, Singh CV (2016) Evaluation of Sires Using Different Sire Evaluation Methods on the Basis of First Lactation Traits in Sahiwal Cattle.J Veterinar Sci Technol 7: 296.doi:10.4172/2157-7579.1000296Effectiveness of different sire evaluation methods for first lactation traits.