Genetic relationship of meat and milk production in Finnish Ayrshire

Livestock Production Science 69 (2001) 1–8 www.elsevier.com / locate / livprodsci

Genetic relationship of meat and milk production in Finnish Ayrshire a, a b Anna-Elisa Liinamo *, Matti Ojala , Johan van Arendonk b

a University of Helsinki, Department of Animal Science, P.O. Box 28, FIN-00014 Helsinki University, Finland Animal Breeding and Genetics group, Wageningen University, P.O. Box 338, 6700 AH Wageningen, The Netherlands

Received 21 March 2000; received in revised form 3 November 2000; accepted 3 November 2000

Abstract Genetic relationships of meat and milk production traits were studied from a field data set of 50 852 Finnish Ayrshire bulls and heifers and 28 362 Finnish Ayrshire cows, using REML methodology and animal model. Studied meat production traits included carcass weight, fatness and fleshiness for all bulls, heifers and cows, and additionally heifer and mature live weights estimated based on heart girth circumference for cows. Milk production traits included first lactation 305-d milk, fat and protein yield, and fat and protein percentage for the all the slaughtered cows. Genetic correlations between bull / heifer and cow meat production traits varied between 2 0.20 and 0.68, with higher and positive correlations between corresponding traits in both data subsets. Genetic correlations between bull / heifer meat production traits and cow milk production traits were either positive and low (with yield traits) or close to zero (with composition traits).  2001 Elsevier Science B.V. All rights reserved. Keywords: Genetic correlations; Dairy cattle; Dual-purpose; Meat and milk production

1. Introduction Knowledge of the appropriate genetic parameters of traits under selection is required for designing efficient selection procedures. For an optimal dualpurpose breeding program in particular genetic and phenotypic parameters between meat and milk production traits are important. Genetic parameters for milk traits in dairy cattle populations, and genetic parameters for meat traits in beef cattle populations are readily available in the literature. However, the literature includes much less *Corresponding author.

reports on the association between meat and milk traits in dairy populations, with most of the studies carried out before 1970s (e.g., Cook et al., 1942; Mason, 1962, 1964; Mason et al., 1972; Langlet, 1965; Martin and Starkenburg, 1965; von SamsonHimmelstjerna, 1965; Soller et al., 1966; Jesswein, 1968; Suess et al., 1968; Langholz and Jongeling, 1972; Calo et al., 1973), and only a few done during the last 20 years (e.g., Colleau et al., 1982; Gere et al., 1983; Syrstad, 1983; Alps and Averdunk, 1984; van Veldhuizen et al., 1991). Most of these studies were based on relatively small scale experiments. In addition, very few estimated the correlation between beef bulls and their female lactating paternal half

0301-6226 / 01 / $ – see front matter  2001 Elsevier Science B.V. All rights reserved. PII: S0301-6226( 00 )00252-9

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sibs. Most studies concentrated on relationships of growth with milk traits, while carcass quality traits such as fleshiness and fatness have received much less attention. A majority of studies agree in finding a zero or slightly positive genetic correlation between milk yield and growth rate, but the situation is less clear for carcass traits. In an earlier study, the genetic parameters were estimated for carcass traits in Finnish Ayrshire bulls and heifers (Parkkonen et al., 2000). The relationships of body weight and carcass traits with first lactation milk production in Finnish Ayrshire cows were also estimated (Liinamo et al., 1999). The objective of this study was to estimate the relationships of bull and heifer carcass traits with the respective carcass traits of dairy cows and their first lactation milk production traits, from the routinely collected field data that was used in the two earlier studies.

2. Materials and methods

2.1. Materials Carcass data was collected in slaughterhouses of Lihakunta Oyj in Northern and Central Finland. For this study, a data set was formed of the Finnish Ayrshire bulls, heifers (female animals who had not calved) and cows (female animals who had calved at least once) slaughtered between the 1st of January 1996 and the 30th of June 1998. There were altogether six slaughterhouses presented in the data set, but over 55% of the bulls and heifers and 50% of the cows had been slaughtered in the biggest one. Only animals that had originated from farms participating in milk recording system were included in the analyses. Information on slaughtered cows’ own first lactation milk production traits was further added to the data. Information on the cows’ estimated live weight based on heart girth circumference was also included if it had been recorded. The restrictions imposed on the bull / heifer data set were as described by Parkkonen et al. (2000), and on the cow data set as described by Liinamo et al. (1999). In the bull / heifer data set, only animals that were slaughtered at the age of 300 through 899 days and having carcass weight of at least 130 kg were

included. In the cow data set were included only cows that had calved for the first time after September 1987 and had completed their first lactation. After restrictions, the final data set used in the analyses included 41 834 bulls, 9018 heifers and 28 362 cows. In this study, the data was divided in two subsets, with bulls and heifers together in one subset and cows in the other subset (Fig. 1). The studied measures for both animal groups included carcass weight and carcass fatness and fleshiness EUROP scores. In addition information was available for the cows on estimated heifer and mature live weight, first lactation 305-d milk, fat and protein yields, and fat and protein percentages. The carcass traits were further described by Liinamo et al. (1999) and Parkkonen et al. (2000), and the live weight and milk production traits by Liinamo et al. (1999). Bulls and heifers descended from 1220 and cows from 1547 different sires, 712 of which were common to both data sets. Altogether 67% of animals had paternal half-sibs in both bull / heifer and cow data sets. There were also 3440 common dams for the two data sets, and 10% of animals had maternal half-sibs in both data sets. Furthermore, 32% of bulls and heifers had their dams included in the cow data set with her own carcass and milk production information. The animals originated from 9123 different herds. Over 40% of herds had observations in both data subsets, i.e., they had sent both cows and either bulls or heifers to slaughter. The average number of observations per herd was 8.7, but almost 17% of herds had only one observation in the total data set. The maximum number of observations per herd was 240 in the bull and heifer data subset and 38 in the cow data subset.

2.2. Methods Carcass weight, fatness and fleshiness of bulls and heifers were analysed with the following linear model: y ijklmn 5 m 1 sex i 1 slho j 1 slyrmo k 1 slagemol 1 a m 1 c n 1 eijklmn where y ijklmn 5carcass weight, fatness or fleshiness of

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Fig. 1. Structure of the data subsets and estimated population parameters (r g 5genetic correlations; r c 5herd correlations).

bulls and heifers; m 5general mean; sex i 5fixed effect of ith sex, (i51–2); slho j 5fixed effect of jth slaughter house, ( j51–6); slyrmo k 5fixed effect of kth year-month class of slaughter (k51–30); slagemol 5fixed effect of lth age class at slaughter (l51–14); a m 5random effect of mth animal; c n 5 random effect of nth herd; eijlkmn 5random residual effect. Carcass weight, fatness and fleshiness of cows were analysed with the following linear model: y ijklmn 5 m 1 slho i 1 slyrmo j 1 slageyr k 1 b*dcalvl 1 a m 1 c n 1 eijklmn where y ijklmn 5carcass weight, fatness or fleshiness of cows; m 5general mean; slho i 5fixed effect of ith slaughterhouse (i51–6); slyrmo j 5fixed effect of jth year-month class of slaughter ( j51–30); slageyr k 5 fixed effect of kth age class at slaughter (k51–8); dcalvl 5regression variable accounting for the number of days from last calving till slaughter; a m 5 random effect of mth animal; c n 5random effect of nth herd; eijklmn 5random residual term. Combined effect of slaughter year and month was presented in calendar months starting from January 1996 and ending in June 1998, resulting in 30 classes. Slaughter age of bulls and heifers was first calculated in months and then classified in 14 classes

(1510, 11 and 12 mo, 2513 mo, 3514 mo, . . . , 12523 mo, 13524 and 25 mo and 14526 to 30 mo of age). Slaughter age of cows was calculated in years and then classified in eight classes (#3, 4, 5, 6, 7, 8, 9 and $10 years of age). Time from last calving until slaughter for cows was presented in days, and it varied from 0 to 729, with an average of 254 days. Cows with number of days exceeding 730 were removed from the data set. Estimated heifer and mature live weight, milk, fat and protein yield, and fat and protein percentage were analysed with the following linear model: y ijkl 5 m 1 clyrse i 1 clage j 1 a k 1 cl 1 eijkl where y ijkl 5estimated heifer or mature live weight, milk fat or protein yield, or fat or protein percentage; m 5general mean; clyrse i 5fixed effect of ith calving year-season class (i51–40); clage j 5fixed effect of jth age class at first calving ( j51–8); a k 5random effect of kth animal; cl 5random effect of lth herd; eijlk 5random residual term. Calving year-season classes were formed for cows from September 1987 onwards by combining three consecutive months into each class. Thus, autumn months September, October and November belonged to one class, as did, respectively, winter months December, January and February, spring months

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March, April and May, and summer months June, July and August. The last calving year-season class was summer 1997, resulting in 40 different classes. Age at first calving was divided in eight classes (#20, 21–22, 23–24, 25–26, 27–28, 29–30, 31–32 and $33 months). The cows with age at first calving under 15 months or over 36 months were removed from the data set. In all analyses, distributions of animal effects (a), herd effects (c) and residuals (e ) were assumed to be multivariate normal with zero means and with Var(a)5As 2a , Var(c)5Is 2c , and Var(e )5Is e2 . When using bivariate models, the expected values of random effects and the covariances between them were assumed zero. The variance of each random effect for the 13 traits (i51–13) in question was assumed 2 2 to be Var(a i )5As ai , i , Var(c i )5Is ci , i , and Var(ei )5 2 Is e i , i . The covariances between the random effects in different traits (i, i951–13 and i ±i9) were assumed to be Var(a i,i 9 )5Asai, i 9 , Cov(c ii 9 )5Isci,i 9 , and Cov(ei,i 9 )5Ise i,i 9 . (Co)variance components for the traits were estimated with the Restricted Maximum Likelihood (REML) method by the program package REML VCE 4.2 (Groeneveld, 1998). All analyses were done assuming the animal model, with pedigree data

including information on two generations, i.e., parents and grandparents, for all bulls, heifers and cows. Estimates of genetic and herd correlations were obtained with bivariate analyses. Genetic correlations were derived from the (co)variance components as r g 5 sai,i 9 /(sai sai 9 ), and herd correlations as r c 5 sci,i 9 /(sci sci 9 ).

3. Results and discussion An average carcass in the mixed bull and heifer data subset weighed 257 kg, and classified as having EUROP-fatness of 2.2 and EUROP-fleshiness of 4.2, i.e., between classes O2 and O (Table 1). This corresponds with a carcass with slight fat covering, profiles from straight to concave, and average muscle development (EUR-OP, 1995). The bull carcasses weighed on average 68 kg more than heifer carcasses and were also slightly better classified for both fatness and fleshiness, while there was more variation in the carcass traits among the heifers (data not shown). The average cow carcass weighed 242 kg, and was classified as poorly muscled with slight to moderate fat covering (Table 1). In general, the data used in this study represented well the overall

Table 1 Number of observations, means, standard deviations (S.D.), coefficients of variation (C.V., %), and minimum and maximum values for studied traits in different data subsets Trait

No. of observations

Bull and heifer data: Carcass wt., kg Fatness, score Fleshiness, score a

50 852 50 755 50 750

257 2.2 4.2

Cow data Heifer wt.b , kg Mature wt.c , kg Carcass wt., kg Fatness, score Fleshiness, score a Milk yield, kg Fat yield, kg Protein yield, kg Fat, % Protein, %

18 963 17 474 28 362 27 731 27 683 28 362 28 362 28 362 28 362 28 362

492 545 242 2.7 2.6 5983 268 197 4.5 3.3

a

Mean

S.D.

C.V. (%)

Min.

48 0.5 1.0

19 23 24

130 1 1

54 61 41 1.0 1.2 1115 51 37 0.6 0.2

11 11 17 37 46 19 19 19 13 6

270 320 109 1 1 855 34 31 1.9 2.3

Original EUROP-fleshiness scores transformed so that P2 51, P52, P1 53, O2 54 . . . R1 59, U511 and E514. Estimated based on heart girth during first lactation. c Estimated based on heart girth during second or later lactation. b

Max. 500 5 14

730 800 471 5 10 11 529 643 417 7.7 4.6

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carcass quality of all the bulls, heifers and cows slaughtered in Finnish slaughter houses during the data collection time (TIKE, 1998). Means of milk, fat and protein yields were lower than the average for Finnish Ayrshire cows in the first half of 1990s (Table 1) (MKL, 1997). In addition, the variation in fat percentage of lactation yield was high, and the difference between the extremes was considerable. Our data consisted only of first lactation records, while the MKL data includes all cows. Also over one third of cows in our data were born already in the 1980s, and the younger cows were in turn likely to have been culled early for low production. The mean estimated heifer and mature live weights of dairy cows were slightly higher than the corresponding averages for the breed in the 1990s (MKL, 1997). Genetic parameters for carcass traits within bull / heifer data were reported earlier by Parkkonen et al. (2000), and genetic parameters for carcass, live weight and milk production traits within cow data by Liinamo et al. (1999). Genetic correlations between analogous carcass traits in bull / heifer data set and cow data set were estimated to be positive and moderate, especially between carcass weights and fleshiness scores of bulls / heifers and cows (Table 2). The other genetic correlations between bull / heifer and cow carcass traits were mostly positive and low, except for the genetic correlations with cow carcass fatness that were negative and low. The herd correlations between carcass traits of bulls / heifers and cows were Table 2 Genetic and herd correlations of bull and heifer carcass traits with cow carcass traits Cows

Genetic correlations Carcass wt. Fatness Fleshiness Herd correlations a Carcass wt. Fatness Fleshiness a

Bulls / heifers Carcass wt.

Fatness

Fleshiness

0.66 20.20 0.25

0.20 0.47 0.18

0.58 20.02 0.68

0.53 0.36 0.51

0.46 0.39 0.45

0.34 0.23 0.41

a

Standard errors of estimates in the range 0.004–0.041.

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all positive and moderate, suggesting a common favourable environmental effect for carcass traits of all animals reared in the same herd regardless of their intended use. The genetic correlations between carcass traits of Finnish Ayrshire bulls / heifers and cows estimated in this study agree generally well with those estimated from Dutch Black and White and Dutch Red and White populations, using the same traits (de Jong, 1997). In the Dutch study the genetic correlations between respective bull and cow carcass traits were higher than in this study, especially between bull and cow fatness. However, this discrepancy could be due to population differences with Dutch animals having considerably higher carcass weight, better fleshiness and higher fatness to begin with as compared to the Finnish Ayrshire. Based on the moderate to low genetic correlations between carcass traits of bulls / heifers and cows in this study, it would seem that in the Finnish Ayrshire the carcass traits of young and growing, and on the other hand fully mature animals can be considered as different traits, especially with carcass fatness. The different relationships between carcass fatness and other carcass traits in bull / heifer data compared to cow data were also established in the earlier studies on the Finnish Ayrshire carcass data. The genetic correlations between carcass fatness and other carcass traits were close to zero within the bull / heifer data (Parkkonen et al., 2000), but positive and moderate within the cow data (Liinamo et al., 1999). These differences in genetic correlations between fatness and other carcass traits in bulls / heifers vs. cows may be due to bulls and heifers being at slaughter at a different point in the growth curve to cows. Bulls and heifers are usually slaughtered when they have already reached their full potential for fleshiness but have not yet started to gain fat, while most cows are allowed to reach full maturity over the usual finishing point of slaughter animals. Unfortunately the bull / heifer data subset was so uniform with respect to the slaughter age, that it was not possible to study the effect that maturing might have had on bull / heifer carcass traits within that data subset. Other possibly influencing factors for the different genetic correlations between carcass fatness and other carcass traits in bulls / heifers and cows might be for example different feeding regimens for

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growing vs. lactating animals, and in the case of cows the effect of milk production on body composition. The genetic correlations between bull and heifer carcass traits and cow estimated live weight traits were positive and moderate for carcass weight, negative and low for carcass fatness and positive and low for carcass fleshiness (Table 3). This was in slight contrast with the respective genetic correlations between estimated live weights and carcass traits of cows themselves, that were all positive and moderate (Liinamo et al., 1999). The herd correlations between bull / heifer carcass traits and cow estimated live weight traits were positive and low to moderate, but lower than the respective herd correlations between cow live weights and cow carcass traits (Liinamo et al., 1999). The genetic correlations between bull and heifer carcass traits and cow first lactation milk production traits were either positive and low (with yield traits) or close to zero (with composition traits) (Table 3). The herd correlations between bull / heifer carcass traits and cow first lactation milk production traits were all low to moderate and positive, suggesting some common favourable environmental effects for

Table 3 Genetic and herd correlations of bull and heifer carcass traits with cow live weight and milk production traits Cows

Genetic correlations Heifer live wt. Mature live wt. Milk yield Fat yield Protein yield Fat, % Protein, % Herd correlations a Heifer live wt. Mature live wt. Milk yield Fat yield Protein yield Fat, % Protein, % a

Bulls / heifers Carcass wt.

Fatness

Fleshiness

0.54 0.56 0.29 0.29 0.32 20.04 0.04

20.09 20.18 0.15 0.19 0.18 0.05 0.04

0.09 0.16 0.08 0.05 0.08 20.04 0.02

0.46 0.40 0.39 0.35 0.39 20.05 0.20

0.33 0.26 0.24 0.25 0.25 0.02 0.13

0.38 0.37 0.29 0.27 0.29 0.00 0.18

a

Standard errors of estimates in the range 0.005–0.040.

both growing and lactating animals in the same herd. However, since the milk data are from 10 years, it is possible that the environmental trend within the herds in this time period has influenced the genetic correlation between milk and carcass traits positively. Thus the genetic correlations found between bull / heifer carcass traits and milk traits in this study may be slightly overestimated. The genetic correlations obtained in this study for bull / heifer carcass traits with cow first lactation milk production traits were mostly in agreement with previous studies (e.g., Cook et al., 1942; Mason, 1962, 1964; Langlet, 1965; Martin and Starkenburg, 1965; von Samson-Himmelstjerna, 1965; Soller et al., 1966; Jesswein, 1968; Suess et al., 1968; Langholz and Jongeling, 1972; Calo et al., 1973; Gere et al., 1983; Syrstad, 1983; Alps and Averdunk, 1984). In some studies also much higher genetic correlations between milk and beef traits of dairy cattle have been estimated (e.g., Mason et al., 1972; Colleau et al., 1982; van Veldhuizen et al., 1991), but in most cases the standard errors of the estimates were very large. The data sets in the previous studies have been usually very small and the methods have been widely varying, but it would seem that the general conclusion is that the genetic relationships between milk production and growth / carcass traits are low. This conclusion is favourable for traditional European production systems, where the majority of beef is produced as a by-product of milk production with dairy or dual-purpose breed animals. As meat and milk traits have either a low favourable connection or no relationship at all, it would seem possible to include both meat and milk in the breeding goal at the same time. Including carcass traits in breeding decisions would not seem to affect the genetic gain in milk traits, while it might bring some extra benefit for the beef producing sector (Liinamo and van Arendonk, 1999). However, based on this study the genetic relationship of especially carcass fleshiness with milk traits is low (Table 3). In order to achieve adequate genetic progress in fleshiness some direct selection pressure should be applied for the meat traits as well. It must be recognised though that selection for more than one trait at the same time will reduce the intensity of selection for any one, so the possible

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inclusion of meat traits in breeding programs of dairy or dual-purpose cattle should be thoroughly studied for each case beforehand from economic point of view.

4. Conclusions In the Finnish Ayrshire, genetic correlations between meat traits of young growing animals and milk traits of dairy cows are favourable for simultaneous genetic improvement in both production systems. However, the genetic correlations between carcass traits of bulls / heifers and milk production traits of cows are so low that the selection pressure through milk traits alone is not enough to improve the meat production traits of bulls and heifers. As a result, some direct selection for these traits should be considered as well.

Acknowledgements The Faculty of Agriculture and Forestry at the University of Helsinki is gratefully acknowledged for the first author’s (A.-E.L.) Young Scientists’ research grant.

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