L-carnitine improves : Part 1
L-carnitine improves egg production in black neck ostriches
A. HajibabaeiA,D, M. ShivazadB, Sh. Golzar AdabiC, A. Lavaf A and N. EilaA
ADepartment of Animal Science, Islamic Azad University, Karaj Branch, Tehran, Iran.
BDepartment of Animal Science, University of Tehran, Tehran, Iran.
CJahad Keshavarzi Organisation, East Azarbayjan, Iran.
DCorresponding author. Email: hajib@ut.ac.ir
Abstract. The important functions of L-carnitine are fostering the oxidation of long-chain
fatty acids by mitochondria and stimulating protein-sparing action by increasing energy
derived from lipids. The present study was conducted to investigate dietary effects of
L-carnitine on egg production of breeder ostriches. Ninety black neck ostrich breeder birds
(60 females and 30 males) were examined randomly (completely randomised design)
within three treatments and five replicates for 7 months in breeding season. A basal diet
was formulated and used for the control group (L1), while two levels of L-carnitine, 250
mg/kg and 500 mg/kg, were included in the basal diet for treatments L2 and L3,
respectively. The egg production percentage, egg weight and defective eggshell percentage
were measured. The supplementary diet with 500 mg/kg L-carnitine increased (P < 0.01)
the egg production percentage. Means (±s.e.) of egg production percentage for L1, L2 and
L3 were 9.68, 12.95 and 17.13% (±1.08), respectively. L-carnitine had no effect on the egg
weight and the defectiveeggshell percentage. The results suggest that basal diet
supplemented with 500 mg/kgL-carnitine. can increase the egg production percentage of
ostriches.
Introduction
L-carnitine is a natural substance that acts in the cells as a receptor molecule for activated
fatty acids. The formula for carnitine, original named vitamin Bt or B11, is C7H15NO3 and
the chemical name is L (-)-3-hydroxy-4-N,N,N, trimethylaminobutyrate. Isomers (D) and (L)
are two chemical structures of carnitine but L is essential for both humans and animals
(Harmeyer 2002).
A deficiency results primarily in impaired energy metabolism and membrane function. The
highest synthesising capacity is found in the liver (Harmeyer 2002) and vitamin C or
ascorbic acid is a cofactor during the two hydroxylation steps in the carnitine biosynthetic
pathway (Neuman et al. 2000).
In neonates the capacity for endogenous synthesis is considerably restricted and develops
only during early life; adult animals have the ability to synthesise the L-carnitine. In this
process, the methyl group is derived from methionine while L-lysine provides necessary
carbon chains and nitrogen. Vitamins B6, B12, C, folic acid, niacin and iron are also
necessary for catalysis of the endogenous synthesis of L-carnitine. The major metabolic
role of L-carnitine appears to be the transport of long-chain fatty acids into the
mitochondria for β-oxidation. Long-chain fatty acids cannot enter the mitochondria and
produce energy. In this process long-chain fatty acids are transferred to acyl-CoA.
L-carnitine performs this shuttle function by replacing the CoA outside the mitochondrion
and transporting the fatty acids into the mitochondrial matrix as acyl-carnitine. Acetyl-CoA
is then regenerated by binding with CoA and releasing L-carnitine. Acyl-CoA enters the
β-oxidation cycle and produces acetyl-CoA. Finally, acetyl-CoA enters the Krebs cycle and
produces energy. Thus, energy production from long-chain fatty acids directly depends on
carnitine (Harmeyer 2002).
The body cannot produce enough L-carnitine to fully cover its own needs thus it needs to
be supplied with extra L-carnitine. L-carnitine occurs naturally in most foodstuffs in varying
amounts. Foodstuffs of vegetable origin normally contain very little L-carnitine. Protein of
animal origin (muscle tissue, blood meal, liver, etc.) and dairy products are rich in
L-carnitine (Harmeyer 2002).
Leibetseder (1995) also reported that increasing L-carnitine in the feed of broiler breeders,
influenced hatchability and produced an 83–87% increase in the hatching rate. A study by
Rabie et al. (1997a) to determine the effect of L-carnitine supplementation on some indices
of egg quality, showed that the percentage of egg white increased, while the percentage of
egg yolk decreased with the corresponding increase of L-carnitine in the diet. However,
dietary L-carnitine did not influence laying performance or external egg quality. With laying
broiler hens, supplemental dietary L-carnitine resulted in an improvement in the albumen
quality of eggs, measured as albumen height and Haugh unit score, during the early and
late stages of the laying period (Rabie et al. 1997a, 1997b). With the increase of the
L-carnitine supplement for broiler breeders, an increase occurred in the amount of
L-carnitine in the yolk, as well as an increase in the hatching percentage (Tizler 1993).
Çelik et al. (2004) conducted a study to investigate the effect of L-carnitine, supplied in
drinking water, on the performance and egg quality of laying hens under high
environmental temperature. Relative albumen weight and height were increased
significantly by supplemental L-carnitine. Liveweight gain, feed intake, egg mass, egg
weight, yolk weight, shell weight, yolk index, egg-shape index, yolk colour score and shell
thickness were not affected by L-carnitine. The effect of L-carnitine and magnesium on
breeder ostriches was determined by Davis et al. (1997). Results from this study showed
that the treated breeders started egg production sooner and produced more eggs than the
untreated breeders. However, there are few scientific publications that deal with the effect of
L-carnitine on the egg production of birds (Leibetseder 1995; Rabie et al. 1997a; Neuman
et al. 2000).
The main objective of the present study was to assess the effect of a diet supplemented
with L-carnitine on egg production of female ostrich breeders during the laying period.
End of Part 1