ON THE ABILITY OF CALVES TO DIGEST HAY
Aarne Mäkelä

Department of Animal Husbandry , University of Helsinki

Received 'May 12, 1960

Microorganisms characteristic of adult cattle start to occur in the rumen of
calves as early as at the age of two months, depending on the food (5). The best
growth of protozoa and microflora is reached when the fodder ration consists of
hay and moderate quantities of grain (11). According to Conrad and Hibbs (3)
the digestibility of cellulose is less when a 2 : 3 ratio of hay to grain is given than
when either 4:1 or 3 : 2 ratios are used.

The calf is able to digest grass at a very early age. According to Me Meekan
(6) calves of 8 to 10 weeks and to Preston et al. (12) calves of 3 weeks can digest
the dry matter of fresh grass as efficiently as a mature cow. In the experiments
of Conrad et al. (2) with four calves aged 5—7 weeks the mean digestibility of
pasture grass dry matter was 72 per cent and that of cellulose 82 per cent.

Conrad et al. (2) have determined the digestibility of alfalfa hay in six calves
less than two months old fed on hay ad lib. The mean digestibility of hay dry matter
was 64 per cent and that of cellulose 63 per cent. The mean digestibility of crude
fibre was in the experiment of Bartley et al. (1) with two calves 41.6 percent
at the age of 9 weeks and 44.3 per cent at the age of 13 weeks. The corresponding
values from the experiments of Pritchard et al. (13) with 8 weeks old calves varied
from 34 to 51 per cent. In these two experiments the hay was practically the only
crude fibre containing ingredient of the ration. According to the digestibility trials
of Dammers et al. (4) with calves aged 60 days and fed on grain and hay, the cal-
ves digested 13 per cent less crude fibre, 10 per cent less crude protein and 4 per
cent less N-free extracts than grown sheep.

Rumen inoculations may increase the digestibility of roughage. Conrad et al.
(2) found that rumen-inoculated calves digested at the age of 5—7 weeks a statisti-
cally significant higher percentage of the dry matter and cellulose ingested than the
uninoculated calves, but the difference in digestibility was temporary. According
to the experiments of Bartley et al. (1) and Pritchard et al. in calves aged from 8
to 13 weeks (13) the administering of aureomycin had no marked or consistent effect
on the digestibility of nutrients, except a reduction in the digestibility of crude
fibre in some cases.

https://www.c-info.fi/en/info/?token=9sA37UjLQmeyEh6q.2ksywpO7_KWmbNiTNtZIAw.IyNADUdkSets3Sc_QAhQYTFwLuDADvpQfE3Ksy82UxD5tHl7ggB9d9oWZidWEF0Oi6bc0NqYxtEobLqeIRfxEKKq4ZqjqdSxsUMLB1Ch0gAqUShCqLAk9yMnWduNKftC19hMHNTWfnbGEOYSxmorrakPgP6sar4Y--rhppnRWbgA_B-1


162

Already at birth or at least two weeks after birth the calf has 8 incisor teeth
and 4x3 premolar teeth. The eruption of the fourth cheek tooth occurs at the age
of 5 to 6 months (15, p. 453).

According to the observations in this Institute six heifer calves consumed
hay at the age of 2 months on an average 0.57 kg, 3 months 1.22 kg, 4 months 2.65
kg, 5 months 3.16 kg, and 6 months 3.82 kg daily, when hay and water were given
ad lib. and milk and grain in moderate quantities (8).

Experimental

On the University Farm Viik three experiments with calves have been carried
out in order to determine the digestibility of timothy hay with some red clover
and cured at an early flowering stage. 16 Ayrshire calves, the ages of which varied
from 2 % to 9 months and with a normal weight development, were used. They
were given hay either entirely or almost ad lib. Also water was given ad lib. The
experimental period lasted a minimum of 10 days. Samples of hay were taken
either each day (Experiment 1), the last four days only (Experiment 2) or once
from the hay reserved for the trial (Experiment 3). The quality of the hay was
roughly the same in different experiments. The samples from faeces were taken
on the last two days in Experiments 1 and 2 and in Experiment 3 only on the
last day;

Before the digestibility trials the calves had been fed on a moderate milk and
scanty concentrate diet while hay and water had been given ad lib.

Lignin was used as tracer. According to the investigation of Salo (14) the mean
digestibility in sheep of lignin from mature hay or from hay cured after blooming
was 1.8^0.6%.

Experiment 1 was carried out in the spring 1954 with five heifer calves and
one bull calf, the ages of which varied from 3 to 9 months. Hay was the only food
and it was given in such large quantities that the refusals made up about one fourth
of the amount given. A new ration of hay was given twice daily. Analyses were
made separately from the hay given and from the refusals. In the dry matter of
the hay eaten by the different calves the ash percentage varied 5.9—6.2, the crude
fibre 38.0—39.0, the crude protein 8.4—9.0, the lignin 9.4—9.5, the percentage
of N-free extracts being about 44. The digestibility of dry matter, organic matter,
crude fibre, crude protein and N-free extracts was determined.

Experiment 2 was carried out in autumn 1957 with six heifer calves and two
cows for the sake of comparison. The experiment was divided into two phases
each with three calves and two cows. The ages of the calves varied from 10 to 22
weeks. The calves received in addition to hay skimmilk and the two youngest calves
also whole milk. Hay was the only food of the cows. The refusals came to 1/10—1/3
of the amount given. A new ration of hay was given twice daily. Because the crude
protein and crude fibre contents in the refusals were of the same magnitude as the
contents in the hay that was offered, the composition is considered to be the same



163

in the eaten hay as in the hay offered. The composition of hay in both phases was
about the same. The dry matter of hay consisted of 7 % ash, 9 % crude protein,
8 % lignin and 56 % membrane substances 1). The digestibility of organic matter,
N-free organic matter and membrane substances was determined.

Experiment 3 was carried out in the spring 1954 with three bull calves and
one heifer aged about seven months, the weights varying between 160 to 180 kg.
After the experiment the calves were slaughtered and the contents of the reticulo-
rumen, omasum, abomasum, small intestine and large intestine were weighed and
sampled. From these samples as well as from the hay and the faeces the percentages
of dry matter, ash, crude protein, and lignin were determined. The percentage of
membrane substances was determined from the hay, the contents of the reticulo-
rumen, and the faeces. On the ground of the analyses from the hay, the contents
of the abomasum and faeces, the digestibility of N-free organic matter and N-free
non-lignin organic matter was estimated in both the proventriculi and in the whole
digestive tract. In the whole digestive tract the digestibility of organic matter and
membrane substances was also estimated. Hay was the only food and it was given
almost ad lib. New hay was offered three times daily at eight hour intervals. In
the hay dry matter the percentage of ash was 7.2, that of crude protein 10.0, of
lignin 8.8, and of the membrane substances 56.6.

Results and discussion

The digestibility of the hay constituents in Experiment 1 can be seen from
Table 1. The calves aged 5-—9 months digested hay about equally when compared
with each other. The youngest calf, aged 3 months, however, digested hay less
efficiently than the older ones. The table shows that in several calves the digesti-
bility of crude fibre is higher than that of N-free extracts. This is so also in adult
cattle, especially when the hay is coarse. It is apparently due to the fact that in
food analysis the main part of lignin belongs to N-free extracts.

Dedermined according to the method of Paloheimo (10).

Table 1. The digestibility of hay in Experiment 1.

Digestibility percentages
Calf Age,

months Dry Organic Crude Crude N-free
matter matter fibre protein extracts

Mari $ 3 45.3 47.5 47.3 24.0 52.1
Harri 5 52.5 54.1 57.4 42.3 53.6
Misa ? 6 50.7 52.4 53.1 44.0 53.6
Misti $ 6 51.2 52.5 54.9 48.2 51.4
Marina $ 6 >/2 55.0 56.8 60.0 49.1 55.5
Maissi $ 9 53.6 55.2 56.8 49.2 55.4

3



164

Table 2. Feeding of experimental animals and the digestibility of hay in Experiment 2.

Feeding Digestiblity percentages
Experimental

animal g S
« £ I>. 'S S «I s I I—?CU r-. Co CO Suj O H i H +*S;o >.;o as 4=SS I £
£ no .5 oc Jr 2 ,i Ä j
> X. m .* 33 -a OS ZoS S»

The first phase of the experiment
Calves:

Aini 10 weeks 1 8 1.5 52.9 57.9 53.0
Alii 17 » 9 3.0 54.8 59.1 56.1
Ano 22 * 6 5.1 54.5 57.6 54.1

Cows:
Lola 5 years 10.7 61.2 62.3 58.2
Lallu 5 » 13.0 61.2 61.2 58.3

The second phase of the experiment
Calves; ! ,

Alma 10 weeks 1 8 1.0 44.9 50.5 47.8
Alla 12 » 9 1.8 54.7 58.6 53.0
Aasa 17 » 9 2.6 62.3 65.2 60.1

Cows:
Nata 3 years 12.2 61.3 62.3 61.9
Lallu 5 » 13.0 61.8 63.2 59.9

The feeding of calves and control cows and the digestibility of hay in Experi-
ment 2 is shown in Table 2. In estimating the digestibility of the hay it has been
assumed that milk is digested completely except for protein. Because the apparent
digestibility of milk protein is not complete and because hay increases the secretion
of endogenic nitrogen in the gut, the digestibility of protein has not been estimated.
Owing to these facts the digestibility of organic matter in calves was 3—6 per cent
lower than that of N-free organic matter. The digestibility of N-free organic matter
in the ration must equal that of the corresponding ingredient in hay, because milk
fat and sugar are almost completely digested in calves (1). The digestibility of
membrane substances in hay has been estimated because the said substances are
characteristic of hay.

Compared with each other the control cows digested hay equally well. The
calves, even when of the same age digested hay with varying efficiency. For instance
the calf Aasa digested hay as efficiently as the cows, while with the calf Alii who
was of the same age the digestibility was considerably less. The calf Aini again
digested hay more efficiently than the calf Alma of the same age. The live weight
of Aini was 81 kg and that of Alma only 67 kg at the age of 10 weeks. The ability
of calves to consume hay also varies considerably. In the investigation carried out
at this Institute (8) the amounts of hay eaten until 6 months of age varied from
270 kg to 370 kg in 17 calves when hay had been given ad lib. from birth.



165

The calves aged 4—5 months seemed to digest hay almost as efficiently as
adult cattle. The calves aged 10—12 weeks, on the other hand, digested hay less
efficiently. o

The feeding of the calves and the digestibility of the hay as well as the fresh
contents in the reticulo-rumen in Experiment 3 are shown in Table 3. In estimating
the digestibility in the proventriculi a principle earlier used, in this Institute was
applied (9): the contents of the abomasum were considered as an excrement of the
proventriculi and the lignin ratio method was used. The share of the proventriculi
in the digestibility of the N-free organic matter and the N-free non-lignin organic

Table 3. Feeding of the calves, digestibility of hay, and the contents in the reticulo-rumen
in Experiment 3.

Digestibility Digestibility in the whole The share of Contents in the
in the digestive tract the proventriculi reticulo-rumen

Calf „ proventriculi % in the digestibility
% % %
aj • ' .. LJ
> bo XT 00
u ffi s « " a « « tse +2 a e c c

S I e
o

6 I 6 I'B E I E 111:
»■a fll Is rs I s »•§«.&•§ f g 1 5|s £ § £; 5 E • s g E; § §8 | |

'v be 5 be h w Si»u O l i; 2 l O l lI 5 * O u bo — bo£o£coO££o£coSS £ o £ c o Ph 5 -S

Puhto lI<J 170 4.41 45.5 50.8 53.4 53.0 59.2 46.7 85.8 85.8 25.1 65.9
Ilta II cJ 182 4.44 50.4 56.4 57.5 57.4 64.2 53.1 87.8 87.9 38.1 75.6
Kaipu II (J 184 4.13 46.8 52.4 57.3 57.1 63.8 52.3 82.0 82.1 39.3 73.5
Sapea 11$ 158 4.07 48.8 54.6 56.6 56.7 63.4 50.3 86.1 86.1 34.4 77.5

matter varied from 82 to 88 per cent of the corresponding digestibilities in the
whole digestive tract. This share is of the same magnitude as in adult cows and
in 7 months old bulls in earlier investigations carried out by this Institute (9). The
digestibility of organic matter in the whole digestive tract was about the same
as in the calves aged 4—9 months in Experiments 1 and 2.

The contents in the reticulo-rumen of 7 months old calves amounted to 30—
40 kg. Because the calves consumed hay almost ad lib. and because eating continued
nearly until the moment of slaughter, these figures possibly represent the class of
magnitude of the physiological capacity of the reticulo-rumen, which is understood
to mean the highest degree of fullness that can occur in the proventriculi as long
as the vital functions are still taking place quite normally (7, p. 17). The share of
the proventriculi in the contents of the whole digestive tract amounted to 2/3—3/4
or to the same amount as in cows (7, p. 69). The contents of the reticulo-rumen
amounted to 15—22 % of the live weight. These precentages are higher than those
found in cows (7, p. 69).

The contents of the different parts of the digestive tract were weighed after
the slaughtering of the four calves aged 3 y 2—4 months and weighing about 100 kg



166

each. During a minimum of 10 days before slaughtering the calves received 9 kg
skimmilk daily and hay almost ad lib. The food was administered three times
daily at even intervals. The amounts of the contents of the reticulo-rumen varied
in different calves from 12 to 15 kg. The share of the reticulo-rumen in the contents
of the whole digestive tract varied from 70 to 75 per cent the percentages being
of the same magnitude as in older calves and cows. The weights of the contents
in the reticulo-rumen amounted to 12-—16 per cent of the live weights the per-
centages being about the same as those in cows but lower than those found in older
calves. These observations agree with the results reported by Me Meekan (6)
according to which the calf at the age of 3 months has a rumen which in relation
to its body weight is as large as that of an adult cow, and which becomes relatively
larger at 5 months.

Summary

Three experiments have been carried out with altogether 16 Ayrshire calves
in order to determine the digestibility of timothy hay cured at the early flowering
stage and containing some red clover. The ages of the calves varied from 2 y 2 to
9 months. Hay was given either totally or almost ad lib. Lignin was used as tracer.

In experiment 1 the ages of the six experimental calves varied from 3 to 9
months. The calves aged 5—9 months digested hay equally efficiently whencorn-pared
with each other. The youngest calf aged 3 months digested hay less efficiently
(Table 1).

In Experiment 2 the ages of the six experimental calves varied from 10 to
22 weeks. In the trial two control cows were also included. The calves aged 10—12
weeks digested hay less efficiently and the calves aged 4—5 months almost as
efficiently as the control cows (Table 2). The ability of calves of the same age to
digest hay was quite variable.

Experiment 3 was carried out with four 7 months old calves. At the end of
the trial the calves were slaughtered and the contents of the different parts of the
digestive tract were weighed and sampled. On the ground of the analyses of the
hay, the contents of the abomasum and the faeces, the digestibilities of N-free
organic matter and N-free non-lignin organic matter in the proventriculi and in
the whole digestive tract were esimated. The share of the proventriculi in the total
digestibility of the said substances was 82—88 per cent (Table 3).

The contents of the reticulo-rumen of the calves in Experiment 3 as well as
those of younger calves aged 3 y 2—4 months were weighed in connection with the
slaughtering. The quantity of the contents in calves of 7 months was 30—40 kg
and that in calves aged 3 y 2—4 months 12—15 kg.



167

REFERENCES

(1) Bartley, E. E. & Parrish, D. B. & Wheatcroft, K. L. 1956. Antibiotics in dairy cattle nutrition.
6. The effects of aureomycin feeding on the apparent digestibility of certain calf rations.
J. Dairy Sei. 39: 319-325.

(2) Conrad, H. R. & Hibbs, J. W. & Pounden, W. D, & Sutton, T. S. 1950. The effect of rumen
inoculations on the digestibility of roughages in young dairy calves. Ibid. 33: 585 592.

(3) Conrad, H. R. & Hibbs, J. W. 1953. The effect of rumen inoculations and the ratio of hay to
grain eaten on the digestion and nitrogen retention in high roughage fed calves. Ibid.
36: 600-601.

(4) Dämmers, J., Dijkstra, N. D. & Frens, A. M. 1951. Proeven omtrent de voedering van kal-
veren gedurende de eerste levensmaanden. Versl. Landsbomvk. Onderzoek. s’Gravenhage.
No. 57. 9. Ref. Nutrition Abstr. & Rev. 1952, 22: 253.

(5) Huhtanen, C. N., Saunders, R. K. & Gall, L. S. 1951. Some differences in adult and infant
rumen flora of cattle on practical rations. J. Animal Sei. 10; 1049 1050.

(6) Mc Meekan, C. P. 1954. Good rearing of dairy stock. Reprinted from the April, May and June
1954 issues of »The New Zealand Journal of Agriculture», p. 1 31.

(7) Mäkelä, A. 1956. Studies on the question of bulk in the nutrition of farm animals with special
reference to cattle. Acta agr. fenn. 85, 130 p.

(8) —» 1958. Viikin opetus- ja koetilalla noudatettu lehmävasikoitten ruokintajärjestelmä. J. Sei.
Agric. Soc. Finland 30: 276 292.

(9) Paloheimo, L. & Mäkelä, A. & Salo, M.-L. 1955. Some quantitative data on the role of the
ruminant proventriculi in the digestion and absorption of nitrogen-free organic matter.
Ibid. 27: 70—76.

(10) Paloheimo, L. & Paloheimo, Irja 1949. On the estimation of the total of vegetable membrane
substances. Ibid. 21: 1 16.

(11) Pounden, W. D. & Hibbs, J. W. 1948. The influence of the ratio of grain to hay in the ration
of dairy calves on certain rumen microorganisms. J. Dairy Sei. 31; 1051 1054.

(12) Preston, T. R. 1956. Studies on the rearing of calves weaned from milk between two and four
weeks of age. Proc. Brit. Soc. of Animal Production, p. 67 77.

(13) Pritchard, G. 1., Newlander, J. A. & Riddel, W. H. 1955. Aureomycin effects —growth and
digestibility studies with identical twin calves. J. Animal Sei. 14: 336 339.

(14) Salo, Maija-Liisa 1958. Lignin studies. 111. Lignin as tracer in digestibility investigations. J. Sei.
Agric. Soc. Finland 30:97—104.

(15) Sisson, S. & Grossman, J. D. 1938. The anatomy of the domestic animals. 972 p. Philadelphia
and London.

SELOSTUS:

VASIKOITTEN KYVYSTÄ SULATTAA HEINIÄ

Aarne Mäkelä

Kotieläintieteen laitos, Helsingin yliopisto

Viikin koetilalla on suoritettu kolme koetta aikaisessa kukintavaiheessa korjatun ja hieman
apilaa sisältävän timoteiheinän sulavuuden selvittämiseksi vasikoilla. Kokeissa oli kaiken kaikkiaan
16 Ayrshire- vasikkaa, joiden ikä vaihteli 2 % 9 kuukauteen. Heiniä annettiin joko täysin tai mel-
kein vapaasti. Ligniiniä on pidetty johtoaineena.

1. Kokeessa 1 oli kuusi 39 kuukauden ikäistä vasikkaa. Näistä 5 9 kuukauden ikäiset sulat-
tivat heiniä keskenään verrattuina suunnilleen yhtä hyvin. Orgaanisen aineen sulavuus vaihteli 52
57 %. Nuorin, 3 kuukauden ikäinen vasikka, sulatti heiniä heikommin.



168

2. Kokeessa 2 oli kuusi 10 —22 viikon ikäistä vasikkäa ja kaksi vertailulehmää. Nuorimmat vasi-
kat, joitten ikä oli 10—12 viikkoa, sulattivat heiniä heikommin kuin vertailulehmät. Typettömän
orgaanisen aineen sulavuus oli edellisillä 51 —59 % ja jälkimmäisillä 62 —63 %. Sensijaan 4 5 kub-
kauden ikäiset vasikat sulattivat heiniä lähes yhtä hyvin kuin lehmät. Samanikäistenkin vasikoittenkyky
sulattaa heiniä vaihteli huomattavasti.

3. Kokeessa 3 oli neljä n. 7 kuukauden ikäistä vasikkaa, jotka kokeen päättyessä teurastettiih.
Rehusta, juoksutusmahan sisällöstä ja sonnasta suoritettujen analyysien perusteella arvioitiin typet-
tömän orgaanisen aineen sekä typettömän ligniinivapaan orgaanisen aineen sulavuudet sekä esimä-
hoissa että koko ruoansulatuskanavassa. Esimahojen osuus näitten aineitten sulavuudessa oli 82
88 %. Typettömän orgaanisen aineen sulavuus koko ruoansulatuskanavassa oli 53 —57 %.

4. Kokeessa 3 olleitten vasikoitten samoinkuin neljän 3 % 4 kuukauden ikäisen vasikan pötsi-
verkkomahan sisällöt punnittiin teurastuksen yhteydessä. Edellisillä sisällön määrä oli 30 —4O kg ja
jälkimmäisillä 12—15 kg.