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Influence of wheat supplementation on intake and digestibility in dairy cows fed autumn grass ad libitum indoors

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HAL Id: hal-00889372

https://hal.archives-ouvertes.fr/hal-00889372

Submitted on 1 Jan 1995

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Influence of wheat supplementation on intake and digestibility in dairy cows fed autumn grass ad libitum

indoors

Remy Delagarde, Jl Peyraud

To cite this version:

Remy Delagarde, Jl Peyraud. Influence of wheat supplementation on intake and digestibility in dairy

cows fed autumn grass ad libitum indoors. Annales de zootechnie, INRA/EDP Sciences, 1995, 44

(Suppl1), pp.210-210. �hal-00889372�

(2)

Influence of wheat supplementation on intake

and digestibility in dairy cows fed autumn

grass ad libitum indoors R Delagarde, JL Peyraud

INRA, Station

de Recherches sur la Vache

Laitière,

35590

Saint Gilles,

France

The supplementation of fresh grass with

a

significant amount of rapidly fermentable cereal (6 kg : Arriaga-Jordan and Holmes, 1986, J Agric Sci, Camb, 106, 581-592)

reduces herbage intake and digestibility. The

aim of this study

was

to determine the effect of lower levels of supplement (wheat)

on

intake

and digestibility in dairy

cows

fed

on a

herbage-based diet.

A ’control’ diet (C) comprising only fresh perennial ryegrass

was

compared to

a

’supplemented’ diet (S) comprising the

same

fresh grass plus 3 kg of pelleted wheat. Three

ruminally cannulated Holstein

cows

(632 kg

live weight) in mid-lactation

were

used in

an

incomplete switchback design during 3 periods

of 12 days, in October and November 1993.

Cows

were

stall fed with grass ad libitum 3 meals per day at 7.30 am, 2 pm and 9.30 pm.

Cows

on

the S diet

were

given concentrate before grass at 7.00

am

and 9.00 pm (1.5 kg

each time). Grass

was

cut

once

daily and

stored at

+

4°C until meal times. Herbage

intake

was

recorded for each period from day

7 to day 11, and digestibility measured from

day 8 to day 12 by total faecal collection. Urine

was

collected with harnesses. On day 10 of

the two first periods, the pH, NH 3 and VFA

contents of the ruminal fluid and blood

urea were

measured 13 times throughout the day,

i.e. at 12 pm, 4

am

and every 90 min from 7

am

to 10 pm.

The

mean

chemical composition of the grass

(per kg DM)

was as

follows : 878 g OM, 223 g CP and 463 g NDF. Cows

on

the S diet showed both higher total OM intake (15.0

vs

14.5 kg/d, P<0.05) and higher milk production (21.1

vs

20.0 kg FCM, P<0.03) than

cows on

the C diet, but milk fat content (39.3 g/kg) and protein content (31.7 g/kg)

were

not affected by supplementation. Herbage OM intake

was

greatly depressed by supplementation (12.4

and 14.5 kg OM for the S and C diets

respectively, P<0.001 This high substitution rate (0.80 kg per kg OM concentrate) is probably due to the positive energy balance (+ 1.1 and 1.4 UFL/d for the S and C diets

respectively ; Faverdin et al, 1991, Livest Prod Sci, 27, 137-156). The organic matter digestibility (OMD) of the whole diet

was

higher for the S than for the C diet (0.832

vs

0.815, P<0.05). For the S diet, herbage OMD

was

estimated by subtracting the indigestible

wheat OM from total feacal output, assuming

that wheat OMD is 0.89 (INRA, 1989, Ruminant Nutrition (ed R Jarrige), London, Paris, John Libbey). In these conditions, supplementation had

no

effect

on

herbage

OMD (0.821 and 0.815 for the S and C diets respectively, P>0.20). Neither the

mean

pH (5.9), the total acidity (138 mmoles/I), the

acetate (62.1 %), propionate (21.6 %) and butyrate (10.7 %) contents in the ruminal VFA,

nor

the postprandial dynamics of ruminal

fermentations

were

affected by supple-

mentation. These results support the absence of variation in herbage OM digestibility and in

milk fat content when wheat

was

given.

Feeding concentrate had little effect

on

N metabolism since ruminal ammonia (290 mg/I),

uremia (45 mg/100 ml) and urine N output (280 g/d)

were

not statistically different

between diets.

Despite

a

high substitution rate,

no

digestive

interaction is expected in high-quality pas- tures with

a

moderate amount of

a

rapidly

fermentable cereal supplement.

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