NationalLibraryOfScotland/medical-history-of-british-india huggingface dataset:
252
THE BLOOD OF DOMESTIC ANIMALS, III [ Vol. XXII, Part IV
summer months. Blood was drawn from the jugular vein before the morning feed
was given. The morphological constituents and blood sugar (total reducing sub-
stances) were estimated in the whole blood. Neutral potassium oxalate was used
as the anticoagulant and the necessary correction made in calculating the cell
volume. The inorganic constituents, viz., calcium, inorganic phosphorus, magne-
sium, sodium, potassium and chlorides, and proteins were estimated in blood serum.
RESULTS AND DISCUSSION
The morphological constituents were determined by the methods described
by Napier and Das Gupta [1946]. The range and the average with standard error
of these constituents are shown and compared with those of the other breeds of
cattle in Table I. It is evident from the Table I that the Kumaoni bullocks,
as compared to the Hariana and Dhanni bullocks, recorded significantly lower
values for all the haematological constituents studied except the white blood
corpuscles.
Haemoglobin. The method of Newcomer as described by Hawk, Osler and
Summerson [1947] was used in estimating the haemoglobin content of the animals.
It varied from 6.2 to 9.2 with an average value of 7.4±0.18 gms. per 100 ml. of
blood. This figure is definitely lower than the one reported by Kehar and Murty
[1945] and Mullick and Pal [1943] for Hariana and Dhanni bullocks respectively.
Red blood corpuscles. The mean red blood corpuscular count was 6.5±0.24
within a range of 4.4 and 8.4 millions per cubic millimeter of blood. Kehar and
Murty [loc. cit.] and Mullick and Pal [loc. cit.] recorded average values of 7.7 and
8.0 millions per c.mm. of blood respectively for the Hariana bullocks. The latter
authors gave a value of 7.9 millions per c.mm. in the blood of the Dhanni bullocks.
White blood corpuscles. The maximum and minimum count for the white
blood corpuscles were 11.9 and 6.4 thousands per cubic millimeter of blood with
an average value of 8.4±0.33. This figure is in agreement with the value given by
Mullick and Pal [loc. cit.] for the Hariana bullocks, but is higher than the values
reported for the Dhanni bullocks.
Corpuscular volume. The average corpuscular volume was 35.3±1.34 per
sent with a range of variations from 24.6 to 46.2.
Corpuscular values (calculated). The average mean corpuscular volume is
54.6±1.1 cubic microns with a range of 43.4 to 63.5 cubic microns. The mean
corpuscular haemoglobin varies between 10.1 and 14.3 micro micro grammes, with
an average of 11.6±0.29. The maximum and minimum corpuscular haemoglobin
concentration is 25.3 and 19.0 per cent respectively, with an average of 21.2±0.40.
All the corpuscular values are lower than those reported by Kehar and Murty [loc.
cit.] for the Hariana bullocks.
Organic and inorganic constituents. The range and the average with standard
error of the organic and inorganic constituents as compared to those of the two
breeds of bullocks are presented in Table II.
Sugar (total reducing substances). Blood sugar was determined by the method
Hagedorn and Jensen as described by Hawk et al., [loc. cit.].
December, 1952 ]
V.
N.
MURTY
AND
N.
D.
KEHAR
253
TABLE II
Showing the organic and inorganic constituents of Kumaoni bullock as compared to
Hariana and Dhanni bullocks.
Constituents
Organic
constituents
Super (Total reduring mrntincrs)
mg/100 ml. bood.
Serum protein gm/100 ml. serum
Inorganic
constituents
Calcium mgm/100 ml. serum
Inorganic phosphorus) mgm/100
ml. serum.
Magnesium phosphorus mgm/100
ml. serum,
Sodium phosphorus mgm/100 ml.
serum.
Potassium phosphorus mgm/100
mlsserum.
Chlorides phosphorus
mgm/100
ml. serum.
KUMAUNI BULLOCK
Maximum
102.3
8.9
11.4
8.3
3.19)
4.89
16.5
4.12
Minimum
70.6
5.1
9.4
4.8
1.71
25.3
11.9
34
Mean with
standard
error
88.1 ±2.06
6.79±0.25
10.5 ±0.10
6.8±0.20
2.35±0.11
3.69 ±15.24
14.0±0.28
38.5±4.42
HARIANA BULLOCK
Mean
[Kehar and
Murty, 1945]
75.6
8.61
10.4
4.26
2.78
..
..
..
Mean
[Mullick and
Pal, 1943]
82.6
..
10.5
2.40
..
..
..
DHANNI
BULLOCK
Mean
[Mullick and
Pal, 1943J
88.3
..
11.1
2.40
..
..
..
The range of blood sugar was from 70.6 to 102.3 with an average value of 88.1±
2.06 mg. per 100 ml. of blood. Mullick and Pal [loc. cit.] noted 88.3 and 82.6 mg.
per 100 ml. of blood of Hariana and Dhanni bullocks respectively. While Kehar.
and Murty [loc. cit.] reported a lower value of 75.6 mg. per 100 ml. of blood for Hariana
bullocks.
Serum proteins. These were estimated by the well known Kjeldahl method as
described by Hawk et al., [loc. cit.]. The mean serum protein content was 6 .79±0 .25
gm. per 100 ml. of serum, with a range of 5.1 to 8.9 Kehar and Murty [loc. cit.]
reported an average value of 8.61 gm. per 100 ml. of serum, a value definitely higher
than for the Kumaoni bullocks reported here.
Inorganic constituents
Calcium, Calcium was estimated by the method of Clark and Collip [1925].
The average calcium content of Kumaoni bullocks is 10.5±0.10 within the limits
of .9.4 and 11.4 mg. per 100 ml. of serum and is in agreement with the calcium content
of Hariana bullocks reported by Kehar and Murty [loc, cit.] and Mullick and Pal
[loc. cit.]. The value of 11.1 mg. per 100 ml. of serum observed in Dhanni bullocks
by Mullick and Pal [loc. cit.] is higher than the one recorded here for the Kumaoni
bullocks.
Inorganic phosphorus. This constituent was estimated by the method of Fiske
and Subbarow [1925] as described by Hawk et al [loc. cit.]. The mean inorganic
254
THE BLOOD OF DOMESTIC ANIMALS, III [ Vol. XXII, Part IV
phosphorus content is 6.8±0.20 within the limits of 4.8 and 8.3 mg. per 100 ml.
of blood sera. The figure reported for Hariana bullocks by Kehar and Murty [loc.
cit.] is significantly lower.
Magnesium. Magnesium was estimated by the method of Fiske and Subbarow
[loc. cit.] as described by Hawk et al, [loc.cit.]. The mean magnesium content of"
the blood serum of Kumaoni bullocks is 2.35+0.11 with a range of 1.71 to 3.19 mg.
per 100 ml. Mullick and Pal [loc. cit.] observed a similar value for the magnesium
content of Hariana bullocks, but Kehar and Murty [loc.cit.] recorded a higher value,
2.78 for this breed. The Kumaoni bullocks exhibited a lower magnesium content
than the Dhanni bullocks. [Mullick and Pal, loc. cit.]
Sodium. The method of Weinbach [1935] was used in estimating the sodium
content of serum. A very wide range of 253 to 489 mg. per 100 ml. was noticed
with an average amount of 369±15.24.
Potassium. The serum potassium was determined by the method of Breh
and Gaebler [1930]. The maximum and minimum values were 16.5 and 11.5 mg.
with an average of 14.0±0.28 mg. per 100 ml. of blood serum.
Chlorides. The serum chlorides were estimated by the method of Whitehorn
[1920-21]. The average chloride content was 385±4.42 within the range of 344 to
412 mg. per 100 ml. of serum.
From the foregoing data, it is observed that the blood composition of Kumaoni
bullocks, which showed lower haematological values as compared to those of pure
bred cattle, compare favourably with the blood picture of buffaloes reported by
Kehar and Murty [1951]. In view of the breed differences, in the haemoglobin
concentration and the red cell count, observed by Manresa and Reyes [1934] and
Mullick and Pal [1943], the low values recorded, for these constituents, in the present
study, seems to be characteristic of the breed. The mean corpuscular volume and
the mean corpuscular haemoglobin of goat blood [Murty and Kehar 1951] are lower
than that of Kumaoni bullocks. The serum calcium and magnesium contents of
Kumaoni bullocks are almost the same as observed in buffalo [Kehar and Murty,
loc. cit.], goat [Murty and Kehar, loc. cit.] and pure bred cattle [Kehar and Murty,
loc. cit., Mullick and Pal, loc. cit.]. The serum calcium content is higher and the
chlorides lower in equine blood [Kehar et al, 1940] as compared to that of Kumaoni
bullocks.
It is observed that the Kumaoni bullocks recorded higher amounts of serum
inorganic phosphorus and blood sugar but lower serum proteins, than the pure bred
cattle, but they compare favourably with buffalo [Kehar and Murty, loc. cit.] and
goat [Murty and Kehar, loc. cit.]. The sodium and chloride contents of goat serum
[Kehar and Murty, loc. cit.] are lower and the potassium content similar to Kumaoni
bullocks. The above findings indicate that not only the blood constituents of
different species of domestic animals differ, but variations are also found in different
breeds of the same species.
SUMMARY
Previous investigations carried out in this laboratory had indicated that there
may be a possibility of variations in the amounts of the constituents of the blood in
December, 1952] V. N. MURTY AND N. D. KEHAR 256
different breeds of cattle. Since Kumaoni bullocks are extensively used for meta-
bolic and physiological experiments, attempts were made to establish the physio-
logical standards for the blood constituents of this breed of cattle. These observa-
tions included the study of the morphological, organic and inorganic constituents
of their blood. The average values with standard error are given below :
Haemoglobin: 7.40±0.18 gms. per 100 ml. of blood; Red blood cell count
6.50±0.24 millions and white cell count 8.40±0.33 thousands per cubic millimeter
of blood; cell volume—35.3± 1.34 per cent; mean corpuscular volume—54.6.
1.17 cubic microns; mean corpuscular haemoglobin 11.6±0.29 micio micro
grammes mean corpuscular haemoglobin concentration 21.2±0.40 per cent;
sugar 88.l±2.06 mgm. per 100 ml. of blood; protein 6.79±0.25 gm., calcium
10.5±0.10 mg., Inorganic phosphorus 6.8±0.20 mg., magnesium 2.35±0.11
mg., Sodium 369± 15.24 mg.; Potassium 14.0±0.28 mg., and chlorides 385±
4.42 mg. per 100 ml. of blood serum.
REFERENCES
Breh, F. and Gaebler, O. H. (1930). J. biol. Glum. 87, 81
Clark, E. V. and Collip, J. B.(1925). J. biol. Chem. 63, 461
Fiske, C. H. and Subbarow, Y. (1925). J. biol. Chem. 66, 461
Hawk, P. B. Osler, B. L. and Summerson, W. H. (1947). Practical Physiological Chemistry
Kehar, N. D., Mohan Singh and Govind Rau, (1940). Indian J. vet. Sci. 10, 88
Kehar, N. D. (1940). Indian J. vet. Sci. 10, 223
Kehar, N. D. and Murty, V. V. S. (1945). Indian J. vet. Sci. 15, 183
Kehar, N. D. and Murty, V. N. (1951). Indian J. vet. Sci. (In press)
Manresa, M. and Reyes, N. C. (1934). Phillip. Agric. 23, 588
Mullick, D. N. and Pal, A. K. (1943). Indian J. vet. Sci. 13, 146
Murty, V. N. and Kehar, N. D. (1951). Indian J. Physiol. 5, 71
Napier and Das Gupta (1946). Haematological Technique
Sen, K. C. and Roy, A. C. (1938). Indian J. vet. Sci. 3, 39
Weinbach, A. P. (1935). J. biol. Chem. 110, 95
Whitehorn, T. C. (1920-21). J. biol. Chem. 45, 449
THE BUFFALO—A REVIEW
By E. S. E. HAFEZ, PH.D. (CANTAB), Faculty of Agriculture, Cairo, Egypt
(Received - for publication on 13 March, 1952)
O NE of the most urgent problems facing milk production in the tropical and
sub-tropical countries, is to find a suitable type of dairy. animal which combines
high milking capacity and tolerance to severe conditions of climate, disease and
defective nutrition. The domestic buffalo is considered the premier milk producing
animal in the tropics. Some of the characteristics of the buffalo render it more
suitable than the cow for dairy farming in other parts of the world as well.
Zoological Status
The buffalo is a member of the ox-tribe, sub-family Bovinae. Five species
of the wild buffalo (Table I) are known to have orginated in the equatorial and
tropical zones in swampy moist districts of low altitudes. Their systematic classi-
fication is mainly based on the distribution of the hair on the body, the colour and
size of ears and size of skulls. The characteristics of the horns are also considered,
namely, their number (from 2 to 4), the degree of flatness, approximation to the
forehead, direction, reflection, length and thickness of the base.
TABLE 1
Origin of wild buffalo (Sub-genus bubalus)
Latin name
Bos (Bubalus) bubalis, L.*
Bos (Bubalus) caffer, L.* or Bos (Syncerus)
caffer, Sparrman†
Bos (Bubalus) mindorensis, L.*
Bos (Bubalus) depressicornis, L.*
Bos (Bubalus) pumilus, L.‡
English name
Indian
African (Cape)
Carabao
Origin
India and Assam
Algoa Bay, South Africa
Mindoro and Philippine
Celebes, Asia
West Africa
Number of
varieties
reported
4
21
1
2
..
*Lydekker [1913]
† Asdell [1946]
‡ Flower and Lydekker [1891]
257
5
December, 1952 ]
E.
S.
E:
HAFEZ
261
TABLE II
Literature on the reproduction of the domestic buffalo
(Indian buffalo and allied races)
Race
Bulgarian
Egyptian
Indian
Indian (Surti)
Philippine
Indian
Philippine x Indian
Italian
Malayan
Cycle length
(Days)
Range
12—28
..
28—30
..
28—46
34—39
20—39
..
30
Mean
21
21
21
..
34
37
31
..
..
Duration
of
Oestrus
(Hrs.)
24—34
12—36
..
..
24
24-
24
..
..
Gestation period
(Days)
Range
303—326
..
310—314
299—325
314—320
287—337
330—340
Mean
315
..
..
313
316
..
311
..
Age at
1st
con-
cep-
tion
(month)
..
15—18
..
36
33
46
26
..
28
Interval between
calving and post-
partum heat
(Days)
Range
14—410
10—76
..
..
24—50
45—53
35—51
..
30—60
Mean
118
35
30
..
35
50
44
..
..
Interval between
calving (Days)
Range
....
..
....
..
367—479
488—582
388—679
..
..
Mean
..
..
..
..
415
520
502J
..
480
Authority
Kaleff [1938]
Hafez [1952 a and
b]
Levine [1943]
Dave [1930]
Ocampo [1939]
Maymone [1945]
Federated Malaya
States
[1920]
Kangaratnan
[1935]
December, 1952]
E.
S.
E.
HAFEZ
263
based on selection, progeny testing and crossbreeding although critical data
on its productive and reproductive capacities is still lacking.
REFERENCES
Asdell, S. A. (1946). Patterns of Mammalian Reproduction. Comstock, New York. 358
Badr-Eldin, A. (1952). Personal communication (Cairo)
Dave, C. N. (1938). Agric. Live-stk. India, 1, 8, 407
Dave, C. N. (1940). Poona Agric. Coll. Mag., 1, 32, 97
Federated Malay States (1936). Ann. Rep. Vet. Dept. 18
Flower, W. H. and Lydekker, R. (1891). Mammals Living and Extinct, London, Adam and
Charles, 360
Haagner (1920). South African Mammals, Witherby, London. 225
Hafez, E. S. E. (1952, a). Proc. IInd Int. Congr. Physiol. and Pathol. Anim. Reprod. Artif.
Insem. Copenhagen
Hafez, E. S. E. (1952, b). Unpublished data (Cairo)
Kaleff, B. (1938). Z. Zucht., 24B, 391
Kaleff, B. (1942). Z. Tierz. u. Zuchtungsb., 51, 131
Kangaratnan, N. (1935). Malay Agric. J., 23, 421
Kothavala, Z. R. (1935). Agric. Live-stk. India. 5, 47
Levine, C. O. (1920). J. Hered., 11, 51
Lydekker, R. (1913). Catalogue of the Ungulates in the British Museum. (Natural History 1913),
British Museum, London 1, 40
Mahmoud, I. N. (1949). *Studies on Some important Features of buffalo semen
Mahmoud, I. N. (1952). Personal communication (Cairo)
Makino, S. (1944). Cytologia (Tokyo)., 13, 247
Manresa, M. and Diapo, D. (1938). Philippine Agric, 26, 870
Markus, J. (1943). Mezogazdas. Kutates, 16, 109 (Anim. Breed. Abst., 14, 208)
Marsb, T. D. and Dawson, V. (1948). Malay Agric. J., 30, 133
Maymone, B. (1945). Ann. Inst. sperm. Zootec. Roma., 3, 5 (Anim. Breed. Abs. 10, 217)
Ocompo, A. R. (1939). Philippine Agric., 28, 286
Polding, J. B. and Lall, H. K. (1945). Indian J. Vet. Sci., 15, 178
Ragab, M. T. and Asker, A. A. (1951). Indian J. dairy Sci., 4, 159
Shortridge, G. C. (1934). The Mammals of South West Africa, 2, Heinemann, London, 439
Sinha, K. C. and Minett, F. C. (1947). J. Anim. Sci., 6, 258
Villeges, V. (1928). Philippine Agric., 17, 747
Villeges, V. (1930). Philippine Agric., 19, 3
Yamane, J. and Ono Y. (1936). Mem, Fac. Sci. Agric. Tailhoku, 19, 87 (Anim. Breed. Abs. 7, 303)
*Fouad I University Thesis for Ph.D. degree, Faculty of Agriculture, Cairo, Egypt
CAUSES OF VARIATION IN BIRTH WEIGHT OF EGYP-
TIAN CATTLE AND BUFFALOES
A. A. ASKER AND M. T. RAGAB, Animal Breeding Department, Faculty of Agri-
culture, Fouad First University, Cairo, Egypt.
(Received for publication on 18 March, 1952)
T HE weight of an animal at any stage of life is a phenotypic expression of its
genetype. The wider the difference between the two expressions, the less impor-
tant is the phenotype as an aid to selection. The part played by environment in the
determination of birth weight seems to be of special importance. Birth weight
is the first measure of the prospective value of the animal's weight and it is more
economical to cull the surplus males in the herd as early as possible. In consider-
ing the birth weight of animals in breeding plans, a full account of the importance
of the different factors causing variation should be known.
This investigation aims at the study of how birth weight in Egyptian cattle,
Pure-bred Shorthorn, Shorthorn grades and buffaloes is affected by genetical and
non-genetical factors. The effect of sex, sequence of calving, month of calving
and the sire of the calf were studied. Also the repeatability and heritability of
birth weight were determined.
MATERIAL AND METHODS OF ANALYSIS
Birth weights of calves from cattle and buffaloes were available on 133 males
and 153 females in the case of buffaloes and 140 males and 130 females in the case
of cows, besides 133 calves of pure and graded Shorthorn of both sexes. All those
calves were born as singles. The calves were born from 1930 to 1950 on the farm
of the Faculty of Agriculture, Giza, Egypt. They were dropped mainly during
Autumn, Winter and Spring; and few cases happened to be born in Summer. The
buffalo calves were sired by seven bulls, while the cattle calves had six sires.
Each bull had seven or more calves. Calves were usually weighed within 24 hours
of their birth and their weights were recorded in kilogrammes.
The analysis of variance for sex and sequence of calving was worked out using
the method suggested by Snedecor and Cox [1935]. In estimating the heritability
of birth weight, the parental half-sibs method suggested by Lush [1948] was used,
RESULTS AND DISCUSSION
Effect of sex and sequence of calving—
The numbers and means of birth weights for cattle and buffaloes are presented
in tables I and II respectively. Tables III and IV show the analysis of variance
for the effect of sex and calving sequence on birth weight for Egyptian cattle and
265
6
266 BIRTH WEIGHT OF EGYPTIAN CATTLE [Vol. XXII, Part IV
buffaloes in the same order. The results show that females are lighter than male
calves at birth in both cows and buffaloes. The difference between the two sexes
is highly significant in both cases. This is in accordance with the findings of Knapp
et al [1941] and Tyler et al [1947].
The average birth weight of buffalo calves was 38.50 and 36.41 kilos for males
and females respectively. In the case of Egyptian cattle the averages were 25.77
and 23.93 kilos in the same order.
Buffaloes in both sexes exceeded cattle in birth weight by 12.73 and 12.83 kilos
in the case of males and females. Such differences are expected since we are deal-
ing with different species of animals.
TABLE I
Numbers and means of birth weight in kilos according to sex of the calf and calving,
sequence of dam for Egyptian cattle.
Sequence
1st
2nd
3rd
4th
5th & 6th
7th & over
Total
and
Average
Number
28
41
25
19
16
11
140
Males
Per cent
20.00
29.29
17.86
13.57
11.43
7.86
100.00
Mean
23.75
25.95
26.60
26.37
26.81
25.81
25.77
Number
26
30
25
12
19
18
130
Females
Per cent
20.00
23.08
19.23
9.23
14.61
13.85
100.00
Moan
21.73
23.40
24.00
25.58
25.37
25.33
23.93
TABLE II
Numbers and means of birth weight in kilos according to sex of the calf and calving,
sequence of dam for Egyptian buffaloes
Sequence
1st
2nd
3rd
4th
5th
6th & over
Total and
Average
Number
24
25
30
17
10
21
133
Males
Per cent
18.05
18.80
22.55
12.78
7.52
20.30
100.00
Mean
36.13
36.40
39.23
41.82
39.20
39.37
38.50
Number
39
24
26
26
20
18
153
Females
Per cent
25.49
15.69
16.99
16.99
13.07
11.77
100.00
Moan
33.67
34.96
36.96
37.16
38.15
40.39
36.41
December, 1952] A. A. ASKER AND M. T. RAGAB 267
When dams get older, the average birth weight of their calves tends to in-
crease. It is more pronounced in the early parturitions, i.e., 1st, 2nd and 3rd
ones in both cases, than it is in the later ones (Tables I and II). This may be due
to the increase in the dams' weights as they advance in age and approach maturity.
Moreover, the analysis of variance set out in Tables III and IV, showed that the
mean square for sequence of calving is highly significant. The interaction between
sex and sequence is not significant in either cows or buffaloes.
This result does not fully agree with other investigations carried out in this
respect. Knapp et al [1941] stated that the first calves were lighter than their
subsequents in birth weight, but beyond that parturition no consistent trend was
evident. On the other hand Tyler et al [1947] reported that calving sequence has
no influence on birth weight of calves after the second calving. Probably, the
different methods used for raising dairy calves as well as the feeding and management
of dairy heifers are responsible for the discrepancies between the results obtained
in this subject.
TABLE III
Analysis of variance of birth weight for sex and calving, sequence in Egyptian cattle
Source of variation
Between sexes
Between Calv. Seq.
Sex. Sequence
Within individuals
Sum of
squares
275.46
393.72
45.68
3,473.00
D. F.
1
5
5
358
Mean
squares
275.46
78.74
9.13
13.46
Significance
H.S.
H.S.
N.S.
—
TABLE IV
Analysis of variance of birth weight for sex and calving sequence in buffaloes
Source of variation
Between sexes
Between Calv. Seq.
Sex Sequences
Within individuals
Sum of
squares
252.36
1,014.53
162.33
11,061.82
D. F.
1
5
5
274
Mean
squares
252.36
202.91
32.47
40.37
Significance
Sig.
H.S.
N.S.
—
6a
268
BIRTH WEIGHT OF EGYPTIAN CATTLE [Vol. XXII, Part IV
TABLE V
Analysis
of variance of birth weight for sires (Egyptian cattle)
Source of variation
Between sires
Within „
Total
Sum of
squares
312.65
2,379.33
2.691.98
D. F.
6
191
197
Mean
squaros
52.11**
12.46
TABLE VI
Analysis of variance of birth weight for sires (buffaloes)
Source of variation
Between sires
Within
Total
Sum of
squares
1,251.95
7,901.73
9,153.68
D. F.
5
222
227
Mean
squares
250.39**
35.59
..
** Highly significant = <.01
Effect of sire and heritability of birth weight—
During the period of this investigation, seven bulls and six buffalo-bulls were
used in cattle and buffalo herds. It is shown in Tables V and VI that the
differences between sire groups in birth weight were highly significant. In other
words some sires tended to produce heavier calves while others produced lighter
ones, than the average.
The same Tables V and VI were utilised in estimating the heritability of birth
weight for cattle and buffaloes. The parental half-sib correlation method was
used since birth weights of dams and sires were not available. Estimates for heri-
tability of birth weight obtained, were .417 and .561 for cattle and buffaloes res-
pectively.
Gregory et al [1950] reported an estimate of .45 for the heritability of birth
weight in beef cattle. When the same authors used smaller numbers they obtained
an estimate of 1.00. They stated that their estimates may be questioned because
of the small number of calves used to evaluate the sires. Tyler et al [1947] reported
that the average estimate of heritability for birth weight was 60 per cent, using