ORIGINAL ARTICLE

Comparative digestibility of low-quality grass hay by two breedsof cattle differing in mature live weightA. L. Lourenc�o1, A. Dias-da-Silva1, A. S. Santos1,2, M. A. M. Rodrigues1, J. W. Cone1,3 and L. M. M. Ferreira1

1 Department of Animal Science, CECAV-UTAD, Vila Real, Portugal

2 University School Vasco da Gama, Coimbra, Portugal, and

3 Animal Nutrition Group, Wageningen University, Wageningen, The Netherlands

Summary

The digestive capacity of the Portuguese native breed of Barros~ao cattle and the Holstein–Friesian breed was mea-

sured when fed meadow hay (72–74 g CP and 641–671 g NDF/kg dry matter), offered either alone or supple-

mented with soya bean meal (150 g/kg dry matter), at maintenance level. Four mature cows of each breed were

used. Average initial live weight (LW) was 457 and 635 kg for the Barros~ao and the Holstein–Friesian cows

respectively. The organic matter digestibility (OMD) of the meadow hay was higher in Holstein–Friesian than in

Barros~ao cows (p < 0.08) whether supplemented or not. The neutral detergent fibre digestibility of the hay was

also higher in Holstein–Frisian when the hay was fed alone (p < 0.08). The soya bean meal supplementation

increased the OMD and the NDFD digestibility of the total diet (p < 0.05), but not the OMD digestibility of the

hay (p > 0.05). The results obtained in this study suggest a higher ability to digest fibre in the large dairy breed

than in the small native breed. This suggestion is also supported by previous findings with sheep breeds largely

differing in mature live weight.

Keywords digestibility, internal marker, breed, genotype

Correspondence A. L. Lourenc�o, Department of Animal Science, CECAV-UTAD, PO Box 1013, 5001-801 Vila Real, Portugal. Tel: +351 259350409;

Fax: +351 259350482; E-mail: analou@utad.pt

Received: 14 November 2012; accepted: 16 May 2013

Introduction

Differences in digestive capacity among breeds

within a given animal species may be interpreted as

the result of feeding behaviour and digestive adap-

tation to survive in distinct environmental situa-

tions (Van Soest, 1994; Dulphy et al., 1995).

However, the scientific information available to sup-

port this hypothesis in ruminants is inconclusive.

Schneider and Flatt (1975) made the most compre-

hensive scientific literature review covering the

information published until the late sixties. They

concluded that in most of the studies, the effect of

breed was not significant. Also Kennedy (1982)

observed no differences in apparent digestibility of

organic matter (OM) or cell-wall constituents

(CWC), between Brahman crossbred (242 kg LW)

and Hereford steers (215 kg LW), fed alfalfa hay or

tropical forage of low nutritive value at 70–80% of

ad libitum intake. However, this study showed dif-

ferences between breeds in site of digestion with

more extensive rumen digestion in Brahman cross-

bred. On the other hand, Hunter and Siebert

(1985) found higher rates of dry matter and CWC

digestion in the rumen of Brahman than in Here-

ford steers (300 kg LW) offered two tropical grass

hays ad libitum.

More recently, Hennessy et al. (1995) reported sim-

ilar findings when the digestibility of low-quality grass

hay supplemented (or not) with protein or non-pro-

tein nitrogen was offered to steers of four different

crossbred genotypes of Brahman and Hereford. Also

Grimaud et al. (1998) found no difference between

Bos taurus and Bos indicus steers (156 and 207 kg LW,

respectively) when comparing the digestibility of a

diet composed of 79% rice straw and a 21% mixture

of cottonseed meal and molasses offered at similar

levels of intake.

Barros~ao is a small native breed of cattle grazing

most of the year in the hills in the north of Portugal.

This breed is reared for meat (mainly veal) production.

During the winter, this breed is quite often fed indoors

with moderate-or low-quality hay, mainly composed

of grass species, which represents most, if not all, of its

diet. It is quite often argued that, like other native

breeds, this breed has developed a higher ability to

Journal of Animal Physiology and Animal Nutrition 98 (2014) 453–457 © 2013 Blackwell Verlag GmbH 453

DOI: 10.1111/jpn.12090

digest CWC than breeds selected for milk production,

such as Holstein–Friesian cows, as an adaptation

mechanism to its natural environment.

Taking into account the information mentioned

above and the absence of any scientific report on the

physiologic characteristics of this native breed, the

digestive capacity of mature females of Barros~ao and

Holstein breeds was evaluated and compared while

being fed meadow hay, usually offered to the Barros~ao

breed during the winter period, with and without pro-

tein supplementation.

Materials and methods

Animals and diets

Eight non-lactating and non-pregnant mature cows

were used in this digestibility study: four were Hol-

stein–Friesians, and four were from the autochtho-

nous Barros~ao breed. The initial live weight (LW) of

the cows was 635 � 148 and 457 � 24 kg respec-

tively. They were housed in a well-ventilated barn

with 17 h light per day and kept on individual rubber-

floored stalls, with access to individual mangers. The

trial took place in Portugal, (latitude 41°19′ N; longi-tude 7°44′ E) during July and August.

The study was divided into two periods. During the

first period, meadow hay was offered to the animals as

sole feed source, and during the second period, 150 g/

kg of the hay DM was replaced by soya bean meal.

Grass plants were largely dominant in the meadow

hay used throughout the study.

Prior to feeding, the hay was coarsely chopped

(ca.4 cm). Diets were offered in restricted amounts

estimated to cover the energy maintenance require-

ments of the cows (AFRC, 1993). The animals were

fed equal portions twice daily at 08:00 and 20:00 h,

with free access to water and mineral blocks. Soya

bean meal was offered at the morning meal before the

hay and was eaten in totally.

Experimental procedure

Each experimental period comprised of 2 weeks of

adaptation followed by 6 days for collection of feeds

and faecal samples. During the collection periods, two

samples of hay and soya bean meal (only in the 2nd

period) were collected daily for dry matter (DM)

determination and chemical analysis. When refusals

were present, they were recorded and sampled for DM

and chemical analyses as described below. Refusals

only occurred with Barros~ao cows, in particular dur-

ing the first part of the experiment when hay was

offered without supplementation.

Digestibility was measured using acid insoluble ash

(AIA) as internal marker (Van Keulen and Young,

1977). Faecal samples were collected using the grab

sampling technique at 08.00 and 20.00 h. Given the

high level of fibre in the diets, a delay time of 48 h

between feeding and faecal sampling was assumed

(Van Soest, 1994).

All samples of feeds, refusals and faeces were dried

after collection in an air-forced oven at 60 °C for 24 h

(feeds and refusals) or 72 h (faeces) for DM determi-

nation and then milled through a 1-mm screen for

later chemical analysis.

Chemical analyses

The ground samples of feeds and refusals were analy-

sed for ash and Kjeldahl-N (AOAC, 1990; methods

942.05 and 954.01, respectively), neutral detergent

fibre (NDF), acid detergent fibre (ADF) and acid deter-

gent lignin (ADL) as described by Van Soest et al.

(1991) and for ether extract (EE) using petroleum

ether as a solvent in a Tecator Soxtec System HT 1043

Extraction Unit (Foss, Warrington, UK). Hemicellu-

lose and cellulose were calculated as the differences

between NDF and ADF, and ADF and ADL respec-

tively. Acid insoluble ash (AIA) was determined as

proposed by Van Keulen and Young (1977). The

bulked samples of faeces were analysed for ash and

NDF as described above.

Calculations and statistical analysis

Digestibility was calculated as:

Digestibility (g/kg OM) ¼ �1� Ci

Cf

�� 1000 ð1Þ

Digestibility of NDF (g/kg OM)

¼ �1� Ci

Cf� Xf

Xi

�� 1000 ð2Þ

where Ci and Cf are the concentrations (g/kg OM) of

AIA in hay and faeces respectively; Xi and Xf are the

concentrations (g/kg OM) of NDF in hay and faeces

respectively.

A one-way factorial ANOVA was performed to com-

pare the chemical composition differences between

the two batches of hay used in the experiment (Steel

and Torrie, 1980). When significant differences

occurred, the Student’s t-test was used to compare

means.

Intake and digestibility data set could not be normal-

ized nor the variances equalized by transformation.

Journal of Animal Physiology and Animal Nutrition © 2013 Blackwell Verlag GmbH454

Cattle breed, live weight, hay digestibility A. L. Lourenc�o et al.

Thus, differences between breed (Holstein–Friesianand Barros~ao) and between diets (meadow hay and

meadow hay + soya bean meal) were analysed

separately using the nonparametric Wilcoxon/Kruskal–Wallis test. The variance analysis of the intake and

digestibility was carried out using the program GenStat

(2011).

Results and discussion

The chemical composition of the two batches of hay

and of the soya bean meal is presented in Table 1. The

two batches of hay were quite similar. However, the

level of CWC was significantly higher (p < 0.05) in

the batch of hay offered with the protein supplemen-

tation, than in the batch of hay fed without supple-

mentation. Comparing these values with earlier

analysed hay samples, grown and harvested under

similar conditions, it can be concluded that the chemi-

cal composition of the hay used in this experiment

falls within the range expected for a typical meadow

hay of the northern region of Portugal.

The DM intake of the diets is presented in Table 2.

As previously mentioned, Barros~ao cows did not eat

the hay completely, despite the fact that they were fed

at maintenance level according to AFRC (1993), this

suggests that or AFRC (1993) overestimates the main-

tenance needs of the autochthonous breed or the

physical limitation to the intake was exceeded by

these diets when the calculated maintenance level

was offered to the autochthonous breed. On a DM

basis, the amount of hay refused ranged between 44

and 121 g/kg DM when no protein was supplemented

and between 30 and 44 g/kg DM when hay and soya

bean meal were offered. The Barros~ao intake behav-

iour explains its lower DM intake per/kg metabolic

body weight (p < 0.05), and it can also explains the

diet effect on intake per kg metabolic body weight

(p < 0.05).

From the analysis of the NDF content of the feed

offered and refused, the NDF content of the feed eaten

was calculated, and it did not differ between breeds

(p > 0.05): 658 and 615 for the Barros~ao, and 641 and

610 g/kg DM basis for the Holstein–Friesian cows,

when hay was offered alone or with soya bean meal

respectively. Thus, it can be concluded that differen-

tial selective intake did not occur.

The OM and NDF apparent digestibility of the diets

are presented in Table 2. As expected, the digestibility

of the OM and NDF of the diets was higher (p < 0.05)

when the hay was supplemented with soya bean

meal, with a high protein content. However, the OM

digestibility of the hay was unaffected by supplemen-

tation (p > 0.05).

The Holstein–Friesian cows OM and NDF digestibil-

ity was higher (P < 0.08) than the Barros~ao cows

when fed only hay. When the soybean meal was

added to the diet, although OM and NDF digestibility

of the total diet were still numerically higher in Hol-

stein–Friesian cows, the difference was only statistical

significant for the OM digestibility of the hay

(p < 0.08). The lack of statistical significance can be

attributed to the low animal number per treatment

(n = 4) and to the slightly lower intake of Barros~ao

breed that might have increased its digestibility. Nev-

ertheless, the results obtained in this study seem to

suggest a higher ability to digest fibre in the large

dairy breed than in the small native breed. This sug-

gestion is supported by similar results observed when

the authors used chromium as marker (Ferreira,

2002).

Considering the crude protein level (72 g/kg DM)

of the hay fed without supplementation (Table 1) and

using the AFRC (1993) recommendations to calculate

its fermentable metabolizable energy (FME) value and

the required amount of effective rumen degradable

protein (ERDP) at a rumen outflow rate close to the

maintenance level of feeding (9 g/MJ of FME;

Table 3), it can be assumed that the complete degra-

dation of the hay nitrogen was not enough to meet

the nitrogen growth requirements of the rumen

microbial population. Clearly, this was not the case

when 150 g/kg of the hay DM was replaced by soya

bean meal, resulting in 135 g/CP kg DM. Given the

short duration of the experiment and the good body

condition of the animals, it must be assumed that

Table 1 Chemical composition of the meadow hay (MH) and soya bean

meal (SBM)

Chemical composition (g/kg DM) MH* MH† SEM SBM

Number of samples 14 14 14

Organic matter 931a 930a 0.98 931 � 1.0

Crude protein (N 9 6.25) 72a 74a 1.27 477 � 2.4

Ether extract 10a 11a 0.49 16 � 3.2

Neutral detergent fibre 652a 691b 7.99 155 � 11.7

Acid detergent fibre 409a 431b 4.77 94 � 21.6

Acid detergent lignin 56a 58a 2.11 5 � 2.1

Cellulose 353a 373b 4.27 89 � 20.7

Hemicellulose 243a 260b 7.69 61 � 11.3

Acid insoluble ash 23a 25a 0.72 1 � 0.5

Mean values in the same row with different superscripts differ signifi-

cantly (p < 0.05).

*Meadow hay used in the experiment without supplementation.

†Meadow hay used in the experiment with soya bean meal supplemen-

tation.

Journal of Animal Physiology and Animal Nutrition © 2013 Blackwell Verlag GmbH 455

A. L. Lourenc�o et al. Cattle breed, live weight, hay digestibility

nitrogen, recycled through saliva and/or diffused

across the rumen wall, filled the calculated gap

between microbial requirements and the degradable

nitrogen of the hay. This mechanism could explain

the lack of effect of protein supplementation on the

hay digestibility.

Despite the digestibility coefficients differences

being numerically small, the finding that the Holstein

breed showed higher ability to digest the low–qualityhay, do not agree with the majority of the literature

reports and with the current beliefs. Considering that

structural carbohydrates represented approximately

two-thirds of the hay OM, the results obtained in this

study suggest that the dairy Holstein–Friesian breed

has a higher ability to digest fibre than the native Bar-

ros~ao breed.

Previous comparisons made in our laboratory with

growing and mature sheep fed mixed diets and cereal

straw or hay supplemented with a protein source,

showed that the ability to digest fibre was also higher

in the improved Ile-de-France breed than in the

native Churra breed (Lourenc�o et al., 2000, 2010; Go-

mes, 2001). These two breeds differ largely in mature

weight, with the LW of the Churra breed being

approximately 60% of that of the Ile-de-France one.

When the ewes were compared, at the same degree of

maturity and given similar levels of feeding, the rate

of passage of feed particles was approximately 90%

faster in Churra than in Ile-de-France (Lourenc�oet al., 2000). This result was later confirmed with

mature animals and at the same level of intake (Lou-

renc�o et al., 2010). It is not known whether, and to

what extent, the same digestive feature, that is, a

higher rumen outflow rate, has been developed by

Barros~ao cattle, whose female mature weight is also

approximately 60% of its Holstein–Friesian breed

counterpart.

Conclusion

In conclusion, the current belief that native cattle,

even of temperate regions, as in this case, exhibit a

higher ability to digest fibrous feeds, than genetically

improved breeds as an adaptation mechanism to its

natural environmental conditions, was not confirmed

in the present study. In fact, our results revealed a

lower ability to digest fibre in the native breed. Fur-

ther studies may reveal specific features of feeding

behaviour and/or of the digestive processes of this

native breed, not yet investigated, such as the selec-

tive intake and the digesta retention time in the

rumen.

Table 2 Diet dry matter intake (DMI), organic matter digestibility (OMD, g/kg OM) and neutral detergent digestibility (NDFD, g/kg NDF) of total diets

and meadow hay (MH) with and without soya bean meal supplementation in Barros~ao (B) and Holstein–Frisian (H-F) cows

MH Breed MH + SBM Breed Diet

H-F B SEM p-values H-F B SEM p-values SEM p-values

DMI

g/kg LW 12.3 12.3 0.19 0.77 12.6 13.3 0.23 0.15 0.16 0.29

g/kg0.75 LW 61.5 56.9 1.04 0.02 62.7 61.5 1.14 0.15 0.65 0.05

OMD

Diet 626 599 7.97 0.04 662 647 6.16 0.15 7.14 0.001

MH* 626 599 7.97 0.04 623 606 5.37 0.08 4.87 1.00

NDFD

Diet 572 538 9.62 0.08 596 577 6.45 0.25 6.92 0.02

*Mean values calculated by difference, assuming OMD of soya bean meal as 880 g/kg OM (INRA, 1988).

Table 3 Estimated energy and protein values of the ingested meadow

hay (MH) diets (per kg DM) with and without soya bean meal (SBM) sup-

plementation

MH MH + SBM

Holstein–

Friesian Barros~ao

Holstein–

Friesian Barros~ao

OMD

(g/kg OM)

626 599 662 647

ME (MJ)* 9.15 8.77 9.67 9.46

FME (MJ)† 8.78 8.41 9.27 9.06

ERDP required

(g)‡

79.0 75.7 83.4 81.5

CP intake (g) 72.0 70.3 134.5 132.8

*ME, metabolizable energy; value obtained by the equation proposed

by Barber et al. (1984): ME (MJ/kg DM) = 0.157*D, where D is the digest-

ible OM/kg DM (AFRC, 1993).

†ME, fermentable metabolizable energy; estimated by the equation pro-

posed by AFRC (1993): [FME] (MJ/kg DM) = [ME] – [ME fat].

‡ERDP, effective rumen degradable protein; assuming that ERDP is not

limiting: ERDP = MCP = 9 g/MJ of FME (at maintenance level of feed-

ing).

CP, crude protein.

Journal of Animal Physiology and Animal Nutrition © 2013 Blackwell Verlag GmbH456

Cattle breed, live weight, hay digestibility A. L. Lourenc�o et al.

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