Agricultural Research Centre, Institute of Animal Breeding, Vantaa, Finland

Frequency of stillborn calves and its association with production traits in Finnish cattle breeds

By U.B. LINDSTROM and V. VILVA

Ms. received 8. 3. 1976

Introduction

Increasing production costs together with decreasing cow numbers enhance the value of the individual calf. It seems probable that this trend, which is noticeable in all Scandinavian countries, will continue. Improvements in management and hygiene are generally considered more important than breeding when trying to increase the calf crop. However, there seem to be fairly large differences both between breeds and between sires of the same breed as to the proportion of live calves produced per female per year, e.g. LINDHB (1966), POLITIEK (1965).

Therefore, at least theoretically, possibilities exist for influencing the number of live calves by selective breeding. Some authors, e.g. BAR-ANAN (1972) and VAN DIETEN (1963), claim that systematic elimination of bulls with a high incidence of stillborn calves may rather rapidly lead to noticeable improvements.

Selection of bulls

As regards selection of bulls two aspects are of particular importance. Firstly, the accuracy with which undesirable bulls can be identified. Secondly, the possible associations between production traits and calving performance. Generally, consi- derably more interest has been paid to the first than to the second aspect, although the latter may in reality be more important.

In addition to the studies already mentioned reference is made to AURAN (1972) and LINDHB (1967, 1974), which contain summaries of much of the work on the effects of sire, age and parity of dam, season, sex of calf etc. on stillbirths.

1. to compare the frequencies of stillbirths in our pure and crossbred cattle, 2. to investigate the influence of genetic and environmental effects on stillbirths, 3. to calculate (for the same bulls) correlations between incidence of stillbirths and

4. to study the influence of varying numbers of sires, progeny per sire and mean

The main purposes of the present study were:

various production traits,

frequencies of stillbirths on the accuracy of heritability estimates.

Z. Tierzuchtg. Zuchtgsbiol. 94 (1977) 27-43 8 1977 Vcrlag Pad Parey, Hamburg und Berlin ISSN 0044-3581/ASThi-Codcn: ZTZBAS

28

Category

Heifer dams

1972/73

1973/74

C o w dams

1972/73

1973/74

U. B. Lindstrom and V. Viiva

Breed group

ay f c f r f r x f r x ay f c

40902 4369 4640 367 122

42127 4123 5289 354 128

137766 17426 7680 8837 5933

140701 14172 11020 8381 4964

Material and methods

ch x ch x unknown ay f c x ay

87 23 8823

95 24 8877

3889 904 12673

1578 942 14981

The material consists of data from milk recorded herds from the operational years 1972/73 and 1973/74. For each operational year some 60000 heifer calvings and close to 200000 cow calvings were available (Table 1). In Finland a stillborn calf is defined

Total

58753

61017

195108

199739

Tabfe I Total number of calvings in the various breed groups

I av = Avrshire, f c = Finncat t l e , f r = Fries ian , ch = Charolais

as one dead at birth or within 24 hours after birth (excluding aboitions). This is a fairly exact classification and preferable to the rather subjective “difficult calvings”, which often is used. The analyses were therefore based on stillbirths as defined above. In addition, the frequencies of abnormal calves for the major breed groups are given. Calvings, where the breed and identification of the parents could not be determined, were separated from the rest of the material.

Differences between means were tested by t-tests (STEEL and TORRIE 1960, p. 372). Correlations between the sires’ performance and progeny tests on one hand and the incidence of stillbirths on the other hand were computed. Both uncorrected and arc sin corrected frequencies of stillbirths were used.

Heifers vs. older cows

According to many studies, e.g. AURAN (1972) and LINDHB (1966, 1967), the diffe- rences in incidence of stillbirths between breeds and cows of varying age are mostly due to differences between first and later calvers. An earlier study in Finland (LIND- STROM (1970) indicates the same. For this reason, and to avoid splitting the material into too many subgroups, the parity and age influence was taken into account by treating first calvers (heifers) as one group and all later calvings as another group.

Frequency of stillborn calves and its association with production traits 29

Heritabilities

Heritabilities were calculated in two ways : 1. treating stillbirths as a characteristic of the calf (from paternal half sib covariances), 2. treating stillbirths as a characteristic of the dam (from covariances between dams

In order to estimate the half sib covariances in each case two analyses of variance were set up: a single classification ANOVA by sires (years separately) and a two-way nested ANOVA by years and sires within years. In each case the sire component of variance was used as an estimate of the half sib covariance (TURNER and YOUNG 1969, p. 114). The covariances were estimated directly from binomial stillbirth data and the downwards bias in the resulting heritability estimates was removed with the following correction (LUSH 1948; DEMPSTER and LERNER 1950):

being paternal half sibs).

P (I-P) h2corr. = h2uncorr.

22

where P = frequency of stillbirths in the population

This correction transforms the values to correspond to an assumed underlying continuously and normally distributed trait. A study by VAN VLECK (1972) indicates that this correction only slightly overestimates the heritability so a decision was made to use it instead of the more elaborate methods of transforming the original data.

z = ordinate at point P of normal distribution

T h e effect of deaths caused by other factors

If a fraction w (w <p) of the calves dies accidentally or entirely due to factors inherited from the other parent (i.e. dam when heritability is estimated from paternal half sib covariance), the z-values ought to correspond to (p - w) instead of p. This doesn't have any great effect when w is small compared top but as w approaches p the effect may become quite large. For instance if p = -02 and the corresponding corrected h2 = .05 (assuming w - = .O) the effect of increasing w is as follows:

w .OOO .001 .005 .010 .c15 .018 h2, .050 .052 .062 .084 .141 .292

Simulation study

In order to estimate the reliability of the h2-values a simulation study of the effect of sample size was done. For a population of sires the underlying stillbirth frequencies were drawn from N (p = .02, 0 = .0055). This results in a corrected h2 .05.

N - .05 402, p (1 - p) ~ 4 ~ 2 ~ 4 x 0.00552 - - ~~

2 P (1 -P) - h2,,,*,. = h - ~ ~ - ZZP OZs + 0 Z c 2, Z2,' 0.04939a

Then 500 samples were generated for groups of sires taken from this population, the corrected ha-values were calculated and their cumulative distribution function was tabulated. Each sample was generated in the following way: 1. A uniform random number u, E (0,l) is generated for each sire i, i = 1, . . . , S. 2. These numbers are transformed into numbers of stillbirths.

30 1J. B. Lindffrom and V. L'ilva

m xi = u, 5 c [ (;) 0 7 (1 - 0;) " -

J = O m

, i = 1 , . . . , s , m = 0, . . . , n

where, 8, = the underlying stillbirth frequency for the irh sire n = number of offspringlsire

The net effect is that each sire gets a number of stillbirths randomly drawn from a binomial distribution corresponding to his underlying stillbirth frequency. For each sample the following ANOVA is set up:

SOURCt DF 55

~~

l y 2 1 2 Betw. sires s-1

2 )' . x - 2 , x , 4 1 n 1 1

Within sires S (n-I)

= the average stillbirth frequency &XI

Sn where p =

Zp = the ordinate of the normal distribution curve corresponding to p.

Results and discussion

Parity

Fig. 1 gives the average incidence of stillbirths in the various breed groups. (Only results based on sufficient numbers of observations are presented). In all pure breeds heifers have a clearly higher proportion of stillbirths than older cows. The differences are, except for Finncattle in 1972/73 (due to the small number of heifer calvings),

stillbirlhr % 4.0

HEIFERS AS DAMS

3.5 19J1/73 B f S 7 3 / 7 4

3.0

2.5

2 . 0

1.5

1.0

. . OLDER COWS AS DAUS

1972 /710 1973/74 -u frray ir. c chray ch. c

Fig. 1 . Frequency of stillbirths in the various breed groups. (Bull + heifer calves). ay - ayrshire; fc = tinncattle; fr = friesian; ch = Charolais

Frequency of stillborn calves and its association with production traits 31

statistically highly significant. The t-values are given in Appendix I. For all three pure breeds the results for cows for the two years agree well, whereas in Finncattle there is a marked increase in stillbirths for heifers from 1972/73 to 1973/74. This is mainly associated with the decrease in numbers of good Finncattle A1 bulls in recent years. Already a few bulls with a somewhat higher proportion of stillborn calves affect the overall average when the total numbers are so small.

Breed differences

As to the differences between the breeds the results are somewhat confusing. The Ayrshire has both years a significantly lower proportion of stillbirths than the Friesian when heifers are dams. In older cows, however, the reverse is true. Also in comparison with Finncattle the Friesian cows have a lower incidence. In a previous investigation (LINDSTR~M 1970) the Friesian had a significantly higher proportion of stillbirths than Ayrshire and Finncattle also for older cows. One possible explanation is that nowadays owners of Friesian cows, who had some calving difficulties as heifers, take extra precautions at the next calving. Although this to some extent can be done through good feeding and care, it is probably mainly achieved by selection of bulls. Both records on the bulls’ live weights and on their calving performance have been available and, almost certainly, utilized. Another contributing reason might be that part of the “purebred” Friesian cows in fact are crossbreds with Ayrshire or Finn- cattle. The breed group of a cow is determined solely on basis of her sire’s breed, and most of our Friesian cows are the result of upgrading. Therefore, a certain proportion of the Friesian calves may have up to y4 of their genes from Ayrshire or Finncattle.

The differences between Ayrshire and Finncattle are small, and only in one year is the incidence in heifers significantly higher in the latter breed.

In summary it can be noted that, in agreement with e.g. ELLEBY and MYGIND- RASMUSSEN (1971) and L I N D H ~ (1967), the breed differences mainly are due to diffe- rences in stillbirths for heifers.

Crossbreds

Unfortunately there were in all crossbred groups too few heifer calvings to allow meaningful comparisons. This is undoubtedly due to the fears farmers have of using large bulls on their Ayrshire and Finncattle cows. In older cows the Friesian x Ayr- shire crosses have in both years a significantly lower incidence than pure Ayrshires. In fact the crossbred average is some 10-18°/0 lower than the average for the pure- breds. Even if this might be taken as a sign of heterosis it could as well be due to selection of the bulls used on the Ayrshire cows.

The differences between Friesian x Finncattle-crosses and pure Finncattle are slight and not significant. Thus it seems that in the way the crossings with Friesian now are done there are no risks for increased stillbirths.

The same seems to be true for crossings with Charolais. Also here the rather low incidence of stillbirths may partly be due to careful selection of both cows and bulls.

Finally it should be mentioned that in matings between unknown sires (majority probably Ayrshire) and Ayrshire females the proportion of stillbirths in heifers was l0,(-unit and in cows 0.6yo-units higher than when an identified Ay-sire was mated with Ay-females. This is probably mainly a reflection of the general level of mana- gement in the herds. Those with poor records are also in other respects likely to take less good care of their animals than herds with adequate records.

32

4 5

4.0

35

3 0

2 5

2 . 0 .

7.5

U. B. Lindstrom and V. Vilva

-

- . - \ .-., .,.qT A5 DAMS

- ..- /+ /:\/\/ - /+ x - * - . _ , ."\. ,

\ ,/oiorR COWS A5 DAMS Fig. 2. Influence of season of calving on frequency of stillbirths in 1973/74. -

I (All breeds bull + heifer calves)

summer months. This is in agreement with AURAN (1972) and L I N D H ~ (1967). Two explanations are possible. Firstly, the cows calving during the pasture period are not as well looked after as cows calving during the indoor feeding season, resulting in somewhat higher losses. Secondly, cows calving in the summer months may be in better condition, giving birth to somewhat larger calves with increased frequency of stillbirths. For heifers two peaks are noted, one in early summer and another in the late autumn and early winter months. The latter may be associated with the feeding practice of heifers. It is still fairly uncommon to give additional feed to heifers on pasture, not even at the end of the period. Some of the animals may therefore not be in optimal calving condition.

Level of milk production

If the level of milk production in a herd can be taken as a measure of the general standard of management, fig. 3 gives an interesting trend. Both for heifers and older cows the highest mortality figures are noted at the lowest levels of production. It

%dd- btrthr 4.0 1 '. 3.5 1 -';re

'* HEIFERS AS DAMS

F&. 3. Influence of level of milk pro- duction on frequency of stillbirths in 1973/74. (All breeds, bull + heifer

calves)

2.5

2.0

<zow mi 1501 3001 35(u 4wr 01 5001 5501 ,bm

level a& production milk, kg 1500 JOW 3500 4000 41W %O 55W 6WO

seems that there are clear differences between herds as regards treatment of animals and the hygienic conditions. The statistically highly significant difference (t-value 9.6) between the 4 lowest production groups and the rest may also to some extent be due

Frequemy of stillborn calves and its association with production traits 33

B r e e d

A y r s h i r e

F i n n c a t t l e

F r i e s i a n

TOTAL

to a smaller average live weight of the cows in the former, resulting in more calving difficulties.

Bull and heifer calves

Table 2 gives the average incidence of stillbirths for bull and heifer calves in the pure breeds. The difference in mortality between the two sexes is mainly evident when heifers are dams, and seems to be more pronounced for the Friesian. These results are

.% s t i l l b i r t h s 1 8 b u l l - 8 s t i l l b i r t h s r~ 9 t - v a l u e EEi2s 8 p t-valui

3 . 2 1 2 . 8 5 2 . 1 1 3 ~ 5 0 . 5 2 . 1 0 2 . 2 7 < 1

4 . 6 8 2 . 8 8 2 . 9 1 3 ~ ~ 5 0 . 2 2 . 0 4 2 . 0 6 < 1

4 . 9 9 2 . 6 4 4.46xxx 4 9 . 2 1 . 8 9 1 . 4 0 2 . 0 2 x

3 . 5 0 2 . 8 3 i i . 2 T x x 5 0 . 3 2 . 0 8 2 . 2 0 < ins

Table 2

Stillbirths for bull and heifer calves and proportion of bull calves in 1973174 Number of observations as in table 1

I Heifers a s dams 1 Cows as dams

% b u l l - c a l v e s b o r n

50 .8

5 0 . 4

5 0 . 8

5 0 . 7

in agreement with those of L I N D H ~ (1967), indicating that the commonly cited 2 to 2.5 times higher mortality for bull calves is not generally valid. The higher incidence of stillbirths for bull calves seems to be associated with a large breed (of dam). It has been noted, e.g. MONTEIRO (1969) and NIELSEN (1965), that the weight of calf in itself is not the crucial thing, but rather the relation between the pelvic dimensions of the dam and the size of the calf. In many smaller breeds, like Ayrshire, Jersey and Finncattle, this relation does not, even for bull calves, as often become as critical as in the Friesian and other large breeds.

In correspondence with many other studies, a somewhat higher proportion of bull calves are born. With increasing age of dam the proportion of bull calves seems to increase, perhaps as a result of the better uterine environment provided by the older

Abnormalities

In table 3 are given the frequencies of abnormal calves born. It should be pointed out that “abnormal” is not necessarily the same as genetically defective, as the classifica- tion of calves is bound to be rather uncertain. It is evident that very few defective calves are born in all breeds, and that the total number of such calves is too small to be of economical importance. Frequencies of the same order as these have been recorded by L I N D H ~ (1967) and STEGENGA (1970).

cow.

Production traits x stillbirths

Sires

Table 4 gives the association between the frequency of stillbirths and various perfor- mance and progeny test results for Ayrshire A1 bulls. When stillbirths are recorded with the bulls as sires of the calves, none of the production traits is significantly

34

H e i f e r s a s dams

1972/73 1973/74 Breed

Ayrsh i r e 0.07 0.05

F i n n c a t t l e 0 .02 0.05

F r i e s i a n 0.06 0 .04

U. B. Lindrtrom and V . Vilva

Cows a s dams

1972/73 1973/74

0.06 0.06

0 . 0 6 0.08

n . o i 0.05

Table 3

Frequency of abnormal calves

Number of observations as in table 1

correlated to the mortality. However, most of the correlations are positive, and especially the ones concerning beef traits of the same order as earlier results (BAR- ANAN 1971 ; LINDSTROM 1970; SOLLER and BAR-ANAN 1974). The positive association between milk production and frequency of stillbirths is partly brought about by a correlation of 0.2-0.3 between milk yield and live weight, the latter being connected to mortality.

Table 4

Correlation between frequency of stillbirths and various production characters for Ayrshire bulls

minimum 100 heifer and 200 cow calvings/sire

a. Calf mortality when bulls are sires of calves

C h a r a c t e r i s t i c

Performance tes t

B u l l ' s b i r t h w t . 365 d . w t . 60-365 d. growth

r a t e

Proqenv t e s t 0

Bulls milk y i e l d dev. f a t % dev.

" daught. l i v e wt.dev.

C o r r e l a t i o n t o f requency of s t i l l b i r t h s

H e i f e r s a s dams

no o f b u l l s -

172 223

218

4 2

42 4 2

-

s, x)

-

.019

.008

-.010

- . l o3 .116 .165

-

s, xx)

.004

.010

-.003

.003

.051

. 2 1 1

Cows a s dams

b u l l s

. 1 2 2

101 -.123 101 I .132

I

@Correc ted f o r no o f daugh te r s . None o f c o r r e l a t i o n s s t a t i s t i c a l l y s i g n i f i c a n t

s2

-

.086

.12!

. 1 1 9

.186 -.139

.139

-

"S, = uncor rec t . f requency of s t i l l b i r t h s

x x ) S , = a r c s i n v % s t i l l b i r t h s '

Frequency of stillborn calves and its association uith production traits

b. Calf mortality when bulls are maternal grandsires of calves

35

C h a r a c t e r i s t i c

? e r f o r m a c e t e s t

3 u l l ' s b i r t h w t . 3 6 5 d . w t .

60-365 d . g rowth r a t e

? r o g e n y tes t

S u l l ' s m i l k y i e l d d e v .

f a t % d e v .

d a u g h t . l i v e w t . d e v

B u l l ' s m i l k y i e l d d e v .

f a t % d e v . d a u g h t . 1 i v e w t . d e v

C o r r e l a t i o n t o f r e q u e n c y of s t i l l b i r t h s

O o f I u l l s s 1

: h e i ....

5 7

78

1 5

135

135

135

:cow .... 161

1 6 1

1 6 1

rs as dams: ...........

.246

. 4 3 2xxx

.410xxx

.152

-.032

.191X

a s dams:"' ........ .050

- .032

.220xx

s2

......

.315x

.4 l o x x x

.38gxXx

. l o 5

- .014

.178

.049

- . 0 4 3

. 217xx

Maternal grandsires

When stillbirths are recorded with the bulls as maternal grandsires highly significant correlations are got between the bull's own performance test and the calf mortality. Between 15 and 19";) of the variation in mortality is thus accounted for by differences in growth rate between bulls. These results are in disagreement with the ones of SOLLER and BAn-AxAN (1974), who in the Israeli Friesian noted a lower correlation in daughters than in mates of sires. O n the other hand, it seems reasonable that a bull may influence the calf mortality more indirectly through his daughters' size, shape of pelvis etc. than directly as sire of the calf. Before definite conclusions can be drawn the results should be checked on a larger material, calculating the correlations for the maternal grandsires keeping the size (growth rate) of the sires of the calves constant. Unfortunately, the present material was not suitable for this.

Keliahilio

It should be emphasized that correlations of this kind are much affected by the sires represented, the accuracy with which their actual calf mortality is estimated and by the selection of bulls and cows. Compare, for example, the present results with those of an earlier study (LIxmrn6si 1974). The influence of the number of calvings per sire is discussed in more detail in connection with the heritability values. Finally, it can be noted that there seems to be only slight differences between using uncorrected or arc sin corrected data.

In summary: the positive sign of the correlations, and especially the fairly high ones between beef traits and calf mortality for heifer daughters, suggest that one- sided selection for production may have undesirable consequences.

36

as dams

L%

0.00

0.82

0.00

0 . 9 0

0.00

0.00

1.64 1.61

-

U. B. Lintisfrom and V. Viha

H%

7.38

5 .63

10.00

5.82

8.57

8.84

5.60 6.61

-

Differences between bulls

A y r s h i r e

Sires of calf (at

(b) Maternal grandsires of calf (a)

(b)

I# I S

I, ,a

Friesian

Sires of calf (a) Maternal grandsires of calf (a)

Finncattle

Sires of calf (a) Maternal grandsires of calf (a)

Charolais

Sires of calf (a)

Highest and lowest frequencies

Table 5 gives the range of variation in stillbirth frequency for the various breed groups. Both when the bulls appear as sires and as grandsires of the calves consider- able differences are noted. Some sires leave less than 1 yo dead calves while for others 8-10y0 of the progeny is stillborn. Similar variation has been noted in many studies, e.g. BAR-ANAN (1972), LINDHE (1967), POLITIEK (1965) and VAN DIETEN (1963).

Table 5 Lowest (L) and highest (H) frequencies of stillborn calves per sire

I no o bull!

254

69 168

4 3

28

3 1

16 11

-

Cows as dams

no of b u l l s

313 186 178

89

63 19

41 12

13

- (a) minimum 100 heifer and 200 cow calvinqs per sire

I, 8 , I (b) 200 'I " 3 0 0 " "

L%

0.28

0.28

0.25

0.25

0 .27

0.35

0 .oo 0.89

1.09

-

8.48

8.22

6.28

4.83

3.99

2.73

4.40 4.35

3.01

-

Due to the relatively small number of Friesian and Finncattle bulls it is not possible to draw any conclusions about breed differences in this respect. Moreover, as noted earlier, there seems to be some variation from year to year, depending on the sample of bulls represented. In Ayrshire, where we in most groups have fairly large numbers of bulls, there seems to be only a slight difference in the range of stillbirth frequency between heifer and cow dams. It is evident that the required minimum number of calvings per sire affects the results. With mean frequencies of stillbirth of 0.5y0, 1% and 2.5y0, the probability of not getting a single stillborn calf, when the bull is evaluated on 100 calvings, is 61%, 37% and 8y0, respectively (Appendix 11). Thus, with the low average incidence of stillbirths noted in our breeds even 200 progeny per sire is not enough to detect the true calf mortality for many of the bulls. This will, of course, affect the reliability of all correlation and heritability analyses.

Frequency of stillborn calves and its association with production traits 37

Repeatability of stillbirths

From a practical point of view the accuracy with which a bull's stillbirth frequency is repeated in future progeny groups is perhaps even more important than the propor- tion of dead calves as such. Table 6 gives the correlations between various measures of stillbirth frequency for the same Ayrshire bulls. The correlations range between 0.25 and 0.63, and are with one exception all statistically significant. Thus, the pro- portion of stillbirths in heifers gives some indication of a sire's stillbirth frequency in

Table 6

Repeatability of stillbirths frequency for Ayrshire bulls

Type o f d a t a

S i r e s o f c a l v e s

Min. 100 h e i f e r c a l v i n g s x min. 200 cow c a l v i n g s 200 'I x 'I 20 0 '!

'' 200 cow I' - 7 2 x " 200 'I I' - 1 3

I' 300 19 - 7 2 19 3 0 0 19 n - 7 3 400 I' 9, - 1 2 ( 8 4 0 0 -3 (( - 7 3

Matern. q r a n d s i r e s o f c a l v e s

Min. 100 h e i f e r c a l v i n g s x min. 200 cow c a l v i n g s ( w i t h i n y e a r )

" 200 cow " - 7 2 x " 200 cow c a l v i n g s - 7 3

3 0 0 I' - 7 2 3 0 0 *I 11 - 7 3

Is 4 0 0 '' - 7 2 9, 4 0 0 *I 8 0 - 7 3

S i r e s o f c a l v e s x mate rn . q r a n d s i r e s of c a l v e s

H e i f e r s as dams (min. 1 0 0 c a l v . p e r s i r e and

cows I' *) lmin. 200 c a l v . p e r s i r e and p e r g r a n d s i r e )

p e r g r a n d s i r e )

! o r r e l a t i o n between i easu res of ,ti 1 l b i r t h f requency

no of b u l l s

2 1 8

5 5

59

35

24

5 7

105

6 0

4 3

18

31

r

. 25ZXx

.400xx

.626xxx

.265

. 534xx

.29BX

.354xxx

. 286x

. 3 1 3 x

.516'

. 4 3EX

older cows, and the result in one year can be used to predict the mortality in the next. These results are contrary to those of KRAUSSLICH and GOTTSCHALK (1975). Likewise, the result for a bull as sire of calves is associated with the results when he is maternal grandsire of the calves. Similar results were got by VOGT-ROHLF and LEDERER (1975). Again we can note that the results are affected by the minimum number of calvings required per sire; to get reliable results one should probably have a minimum of 300 calvings per sire.

Heritability

The main results are given in table 7. The estimate for the Friesian breed is based on insufficient numbers and given only for comparison. There is a tendency for the h2- estimates to be higher in cow dams than in heifer dams. This may mainly be a reflec-

38 1J. B. Lind&otn and V. Vi l va

Table 7

Corrected heritabilities (h2) of stillbirth frequencies in Ayrshire

pooled data for 1972173-1973174

Category

H e i f e r dams

B u l l s s i r e s o f c a l v e s ” g r a n d s i r e s o f c a l v e s

Cow dams

B u l l s s i r e s o f c a l v e s ( F r i e s i a n )

B u l l s g r a n d s i r e s o f c a l v e s

No o f s i r e s

293 199

41 2

( 8 5 )

2 7 1

T o t . no o f c a l v e s

53 858 54 605

227 848 ( 3 6 6 2 4 )

141 947

2 . 7 0 2 . 8 6

-

8 . 2 2 ( 5 . 4 0 )

4 . 9 2

tion of the greater accuracy with which the “true” calf mortality is estimated in the former category of dams. In the literature there is no clear cut trend.

In general the heritabilities are in fair agreement with earlier studies (see e.g. summary table in LINDHB (1974, p. 661), indicating that with proper recording selection against high incidence of stillbirths should have some effect.

In addition to the estimates of table 7 heritabilities were separately calculated for heifer and bull calves. These showed that in heifer dams the h2 of stillbirths for bull calves was 1.4 to 1.6 times higher than for heifer calves. In cow dams on the other hand there was no difference between the heritabilities. Although these results, of course, are much more unreliable than those for the whole material, they are in accordance with what one would expect from the clear difference in average mortality between the two sexes in heifer dams.

Even when based on data from two years it is difficult to get reliable h2-values. The estimates for heifer dams in table 7 are based on too few observations (see also fig. 4), especially when taking into account that the possible downward bias from mortality due to accidental reasons may easily be of the order 20-30% (see section heritability in Material and methods). In cow dams the number of observations is sufficient, and even with allowance for the above bias the heritabilities can be regarded reliable.

Finally, it can be noted that the h2-estimates for the different recording years were in fair agreement and that the yearly fluctuations accounted for a negligible propor- tion of the total variation in stillbirth frequencies.

Simulation study

Figure 4 gives the main results from the simulation study of the accuracy of h2- estimates based on samples of varying size. It is evident that it is impossible to get reliable results when the number of sires sampled is small and the bulls are evaluated on less than 200 progeny. Even with 500 sires, each sampled with 200 progeny, the 95% confidence intervals for a true heritability of 5% are 2.8 to 7.5%. With only 100 sires available one must get some 750 progeny per bull for the same accuracy.

Frequency of stillborn calves and its association )with production traits 39

100 BULLS

h' %

14

I 9' I . ,

50 loo zoo 300 400 so0 600 700 150 m o w o 1000 number of proqeny pe r bull

A

200 PROGENY PER BULL

50 I00 250 500 number of bulls

C

I000

500 BULLS

I

50 100 200 300 4000 500 600 700 750 POO 900 ioaa number of proqeny per bull

B

Fig. 4. Confidence intervals (95,75 and SO",) for heritability estimates of stillbirth frequency based on samples of varying size when the true heritability is S o , . A = 100 bulls sampled on varying progeny numbers; B = 500 bulls sampled on varving progeny numbers; C = varying numbers of bulls

sampled on 200 progeny

Thus it seems that a minimum of 250 sires, each sampled on 300-400 progeny, is required before the h2-estimates can be treated with any confidence. This means that several of the heritabilities of stillbirths given in the literature are based on insufficient data. In practice, at least in countries with fairly small recorded populations, one must utilize data from several years to get reliable results. Even then it might prove difficult to get enough data for estimating the heritability of stillbirths in heifer dams. One way of getting more data would be to develop simple systems for registering stillbirths also in herds not belonging to milk recording.

Summary

Data from milk recorded herds from the operational years 1972/73 and 1973/74 were analysed. Each year consisted of some 60000 heifer calvings and almost 200000 calvings for older cows. The ana- lyses were based on the number of calves dead at birth or within 24 hours after birth (excluding abortions). The main findings were:

40 U. B. Lindsfrom and V . Vilva

1. In all pure breeds older cows had significantly lower incidence of stillbirths than heifers. Ayrshire

2. Both in heifers and older cows significantly more stillbirths occurred in the summer. 3. Both in heifers and cows the frequency of stillbirths was significantly higher at low levels of milk

production (< 3500 kg) than at higher levels, presumably because of poorer management and hygiene in the former.

4. In heifer dams bull calves had a significantly higher mortality than heifer calves. In older cows this difference was significant only in the Friesian. Of all calves, on an average, only 0.05-0.070,; were registered as abnormal at birth.

5. When bulls appear as maternal grandsires of calves significant correlations of c. 0.4 were got between the bull’s own beef performance test and his calf mortality.

6. Calf mortality for individual Ayrshire bulls with min. 200 heifer calvings and 300 cow calvings ranged from 0.8 to 5.8% in heifers and from 0.2 to 8.2 in cows. Repeatabilities of 0.4 to 0.6 were got between various calf mortality measures for the same bulls.

7. Computer simulation studies showed that when the true heritability of stillbirths is 5yo, estimates based on (a) 100 and (b) 500 sires, each with 100, 400 and 750 progeny, the 95% confidence intervals are for (a) < 0 to 1674, 2 to 9.2yn and 2.9 to 7.4%, for (b) 1.4 to 9.6y0, 3.7 to 6.4% and 4.1 to 5.9%, respectively.

8. Heritabilities of stillbirth frequency ranged from 2.7% in heifer dams to 8.2”/0 in cow dams.

~ 2.1-2.2 versus 2.8-3y0, Friesian 1.6 vs. 3.8%, Finncattle 2.0-2.2 vs. 2.6-3.8:;.

Resumen

Frecuencia de terneros muertos al nacery su reiacion con caracteristicas del rendimiento en raxas bovinas finlandesas

Se analizaron 10s resultados de rodeos con registros de lactacion durante 10s aiios economicos 1972/73 y 1973/74. En cada aiio se contaba con 60000 partos de vacas primerizas (vaquillonas) y casi 200000 partos de vacas mas viejas. El analisis se refiere a la cantidad de terneros muertos a1 nacer o muertos dentro de las 24 horas post-parto (sin incluir abortos). Los resultados mas importantes fueron 10s siguientes: 1. En todas las razas Duras las vacas vieias tenian cantidades significativamente menores de terneros -

muertos a1 nacer que las vaquillonas. Ayrshire 2.1 hasta 2.2 contra 2.8 hasta 3%, Friesian 1.6 contra 3.8%, raza Finlandesa 2.0 hasta 2.2 contra 2.6 hasta 3.80/;.

2. Tanto para vaquillonas como para vacas, la frecuencia de terneros muertos a1 nacer durante el verano era significativamente mayor.

3. En vaquillonas y vacas la frecuencia de terneros muertos a1 nacer para rodeos con un nivel producci6n bajo era significativamente mas alto, que en rodeos con mejores rendimientos, segu- ramente debido a un ma1 manejo y peores condiciones de higiene en 10s rodeos con bajo rendi- miento.

4. Los terneros machos de vaquillonas tuvieron una mortalidad significativamente superior a 10s de vacas. En vacas m8s viejas esta diferencia era estadisticamente significativa s610 para la raza Friesian. En promedio, s610 un 0,05-0,070/, de todos 10s terneros nacidos habia sido registrdao como anormal.

5. Para abuelos maternos pudo encontrarse una correlaci6n de 0,4 entre crecimiento propio y la mortalidad de sus terneros.

6. La mortalidad de terneros hijos de toros Ayrshire individuales con a1 menos 200 partos de vaquil- lonas y 300 partos de vacas se movia entre 0,8-5,8% en las primeras, de 0,2-8,27$ en las segundas. La repetibilidad para las diferentes mediciones de mortalidad de terneros hijos de un mismo tor0 era de 0,4-0,6. Estudios de simulaci6n mediante el us0 de computadoras dieron como resutado, que asumiendol una heredabilidad autkntica de un 5%, 10s estimadores que se basan en 100 toros A y 500 toros B, con 100, 400 o 700 descendientes, dentro de un 95% de interval0 de confianza, se movian para A desde 0 hasta 16%, 2 a 9,2% y 2,9 a 7,4:4, respectivamente, y para B de 1,4 a 9,6%, 3,7 a 6,4% y 4 , l a 5,9%, tambitn respectivamente. Las heredabilidades estimadas para la frecuencia de terneros muertos a1 nacer oscilaban entre 2,6%, para las madres de vaquillonas y 8,3% para las madres de vacas.

7.

8.

Zusammenfassung

Haufzgkeit von Toigeburf en und h e Beziebung xu Leistungseigenschaffen bei finnischen Hinderrassen

Ergebnisse von milchleistungsgepriiften Herden der Wirtschaftsjahre 1972/73 und 1973/74 wurden analysiert. In jedem Jahr standen 60000 Abkalbungen von Erstlingen und fast 200000 Abkalbungen von alteren Kuhen zur Verfugung. Die Analyse bezieht sich auf die Zahl der totgeborenen oder

Frepmcg of s/illborn calves and i f s associufion with production fruits 41

innerhalh von 24 Stunden nach Gehurt eingegangenen Kalher (Ahorte nicht eingeschlossen). Die I-Iauptresultate waren folgende: 1. In allen reinen Rassen hatten alterc Kuhe signifikant weniger Totgehurten als Kalhinnen. Ayrshire

2,l his 2,2 gegen 2,8 his 3<;6, Fricsen 1,6 gegen 3,8:,,, Finnische Rindcr 2,O bis 2,2 gegen 2,6 bis 3 ,84 .

2. Bei Kalhinnen wic auch hei Kuhcn war die Haufigkeit von Totgehurten im Sommer signifikant hiiher.

3. Bei Kalhinnen und Kuhen war die Haufigkeit von Totgehurten in Herden mit niedrigem Pro- duktionsniveau signifikant hiihcr als in hesseren Leistungsherden, wahrscheinlich wegen des schlechteren Managements und dcr schlechteren Hygiene in den Herden mit geringer Leistung.

4. Bei Kalhinnen hattcn Stierkalher signifikant hohere Mortalitat als Kuhkalber. In alteren Kuhne war dieser Unterschied nur hei den Friesen statistisch signifikant. Im Durchschnitt aller Gehurten waren nur 0,05 his 0,07", der Kalher als abnormal registriert.

5. Bei mutterlichen GroRvatern wurde einc Korrclation von erwa 0,4 zwischen ihrer eigenen Zuwachsleistung und der Mortalitat ihrer Kalber beobachtet.

6. Die Kalbersterhlichkeit einzelner Ayrshire-Stiere mit wenigstens 200 Ahkalhungen von Kalhinnen und 300 Ahkalhungen von Kuhen hewegte sich zwischen 0,8 his 5,8'j,, bei Kalbinnen und 0,2 his 8,2'j,, hei Kuhen. Wiederholbarkeit von 0,4 his 0,6 wurde fur die verschiedenen Mane fur Kalher- mortalitat des selhen Bullen heobachtet. Computersimulationsstudien ergahen, daR bei einer echten Heritahilitat von Totgeburten von 5':(] die Schatzwerte, die auf A 100 und B 500 Vaterticrcn mit je 100, 400 oder 750 Nachkommen beruhen, 950, Konfidenzintervalle haben bei von A -: 0 his 160,,, 2 his 9,204 und 2,9 his 7,49,, hei B 1,4 his 9,6, 3,7 his 6,4 und 4,l bis 5,9:b.

8. Heritahilitatswerte fur die Haufigkeit von Totgehurten schwankten zwischen 2,6q,, fur Kalhinnen- mutter bis 8,2':, fur Kuhmuttcr.

7.

References

AURAN, T., 1972: Factors affecting the frequency of stillbirths in Norwegian cattle. Acta Agr. Scand

BAR-ANAN, R., 1971 : Einige Prohleme bei der Zucht des Zweinutzungsrindes. 2ucht.kunde 43,7676. - 1972. Heritahilitatsschatzungcn ciniger Ahkalhemerkmale. 2ucht.kunde 44, 360-367. BECII-ANDERSEN, B., et al., 1971 : Afkomprofer for kodproduktion. (Progeny testing for meat pro-

DEMPSTER, E. R.; LERNER, I.M., 1950: Heritability of threshold characters. Genetics 35, 212-236. VAN DIETEN, S. W. J., 1963: Mortaliteit van kalveren hii de partus a terme van M. R.1J. Runderen.

(Summary: Stillbirth in bovine cattle.) Diss. Univ. Utrecht. ELLEBY, F.; MYGIND-RASMUSSEN, V., 1971 : Kaelvningsstatistik. (Calving statistics.) Landburgs-

ministeriets produktivitetsutvalg. Husdyrhrugsut. meld. 4 (Denmark). KRAUSSLICH, H. ; GOTTSCHALK, A., 1975 : Die Erfassung der Kalbersterhlichkeit und des Gehurts-

verlaufs in der Besamungszucht. D . Tierzuchter 27, 8-10. LINDIIB, B., 1966: Dead and difficult births in cattle and measures for their prevention. World Rev.

Anim. Prod. 4, 53-57. - 1967 : Studier over frekvensen dndfodda och misshildade kalvar inom svenska notkreatursraser.

(Summary: Studies on the rate of stillbirths and congenital ahronmalities in Swedish cattle breeds.) SHS Medd. 13.

- 1974: Improvement in beef-breeding by selection. 1st World Congr. Gen. appl. to Livest. Prod. 1, Plenary Sessions: 655-669.

LINDSTROM, U., 1970: Frekvensen dodfodda kalvar hos niithoskapsraser i Finland. (The frequency of stillborn calves in cattle breeds in Finland.) Finl. Ayrshirehosk. 44, 177-180.

- 1974: Points of view on performance testing dual purpose hulls. 2. Tierzuchtg. Zuchtgsbiol. 91, 11-21.

Imsri. 1. I>.. 1948: The Genetics of PoDulations. Mimeo notes. DeDt. Animal Husbandrv. Iowa State

22, 178-182.

duction.) IV. 392. heretn. fra forsogslabor. Kohenhavn 645., Denmerk.

, I

Cbflege', Ames. P. 325ff. MAIIALA. K.. 1964: Fertilitv as a hrcedine Drohlem in artificiallv bred DoDulations of dairv cattle.

i. Registration and heritability of fcrnil; fertility. Ann. Agr.'Fenn. i, 1: MowrEIRo, L.S., 1969: The relativc size of calf and dam and the frequency of calving difficulties.

Anim. Prod. 11, 293-306. NIELSEN, J., 1965 : En undersogelsc over sammen haengen mellan krydsets og haekkenindgangens

dimensioner hos kocr. (A study on the association between the dimensions of the hind quarters and the pelvic entrance in cows.) Forsogslahor, arhog (1965) 239-261.

POLITIEK, R.D., 1965: Fertility as a breeding problem. World Rev. Anim. Prod. 4, 59-66. ROBERTSON, A.; LERNER, I.M., 1949: The heritability of all-or-none traits. Viability of poultry.

Genetics 34, 395-41 1.

42 KJ. B. Lindrtroni and C'. C'iiva

a y (H vs 0)

f c ( H vs 0)

f r (H v s 0)

SOLBU, H., 1972: Beregning av arvbarheten pa enten eller karakterer. (Estimating heritability for all or none traits.) Seminar at Inst. of Anim. Genet. and Breeding, Agric. College of Norway (mimeo 19 pages).

SOLLER, M.; BAR-ANAN, R., 1974: Correlated effects of selection for rate-of-gain in dairy cattle. 1st World Congr. Gen. appl. to Livest. Prod. 3, (symp) 689-691.

STEGENGA, T., 1970: Kongenitale Minbildungen beim Rind-Ursachen und Mafinahmen. Zichthyg. 5: 4-11.

TURNER, HELEN NEWTON; YOUNG, S. S.Y., 1969: Quantitative Genetics in Sheep Breeding. Macmillan of Australia 1939 ; 332 pp.

VAN VLECK, L.D., 1972: Estimation of heritability of threshold characters. J. Dairy Sci. 55, 218-225. V0G.r-ROHLF, 0. ; LEDERER, J., 1975: Moglichkeiten einer Nachkommenschaftsprifung auf Kalbever-

luste und Schwergeburten an Hand von Feldmaterial. Europ. Assoc. for Anim. Prod., 26 annual meeting Warsaw, Poland, June 1975, (mimeo).

Authors' aridrers: Dr. U.B. LINDSTROM, V. VILVA, Agricultural Research Centre, Institute of Animal Breeding, Box 18,01301 Vantaa 30, Finland

1 0 . 6xxx

1.5%

7. BXXX

Appendix I

Statistical significance of differences between heifers and cows and the breed groups

I f r x a y vs a y (H)

fr x a y vs a y (0)

fr x fc vs fc (H)

f r x f c vs fc (01

c h x a y v s a y (0)

c h x f c v s f c (0)

t - v a l u e

1972/73

< 1"s

2 .gXx

< 1"5

< 1%

1.6"s

< 1"s

f r vs a y (H)

f r v s a y (0)

f r vs f c (H)

f r v s f c (0)

4. lXXX

3. lXx

5.6xxx

2.4x

a y vs f c (H)

a y v s fc (0)

< 1"s

< 1"s

1973/74

10 .5xxx

6. 3xxx

7.7xxx

3. lXx

3.4xxx

< 1"s

1.4%

2 .gXx

< 1%

< 1"s

3.4xxx

1.4%

< 1"5

c h x a y vs f r x a y (0) < 1"s

c h x f c vs f r x f c ( 0 ) l < 1"'

f c = f i n n c a t t l e

f r = f r i e s i a n c h = c h a r o l a i s

H = H e i f e r s as dams 0 = O l d e r cows a s dams

< 1"s

1.79"'

1.42"'

< 1"s

Frcqimcv of stilhortl calves ond ils assooalion tjl;th production /roils 43

Appendix I1

Probability (1') of getting no stillborn calves at varying mean levels of mortality and at varying progeny numbers. Calculated from:

g? (1 -- q) " > 4 (1 - s> 1' = y ! (n - y)!

where n = total number of progeny/sire y = number of stillborn calves (zero) q = mean frequency of stillbirths in population

Probability o f zero shll births

no of caIvinqs/sire