All experimental procedures were approved by the Animal
Care Committee of INRA in accordance with the ‘Use of Vertebrates
for Scientific Purposes Act’ 1985. The animals were
recruited to experiments and allocated to treatment groups
according to milk yield, milk fat and protein content, parity stage of lactation and genotype score at the aS1-casein
locus. Goats of the ‘middle-type’ aS1-casein genotype content
were used to avoid any effects on milk traits(18) or FA composition
(19). A total of fifteen multiparous (3·1 (SD 1·2) lactations)
Alpine goats in mid-lactation (91 (SD 7·7) d in lactation)
were given three experimental diets according to a replicated
3 £ 3 Latin square design with 21 d experimental periods, with
five groups of three animals each. From the fifteen goats
recruited, one animal was withdrawn from the experiment
due to mammary cysts. Each experimental period consisted
of a 14 d adaptation to treatments (which was sufficient to
achieve a full response of milk FA secretion in goats)(3) and
a 7 d sampling period. Goats were housed in a metabolism
unit in individual stalls. The animals were allowed continuous
access to water and were milked at 08.00 and 16.00 hours.
Experimental diets were formulated to meet energy and protein
requirements(20). The three diets were offered as two
equal meals at 08.30 and 16.30 hours. Diets were comprised
of natural grassland hay that was offered ad libitum, with
either a high level of forage (0·8 kg/d) and supplemented
with 130 g/d sunflower-seed oil (F; 6·9% of diet DM; sunflower-
seed oil from Auvergne Trituration, Lezoux, France),
or a high level of concentrate (1·4 kg/d) with maize grain
(CM; 1 kg/d; 5·4% of diet DM) or flattened wheat (CW; 1 kg/
d; 5·5% of diet DM) as source of starch and supplemented
with 130 g/d sunflower-seed oil.