Abstract
Background:
The fertility and genetic value of the flock can be enhanced by selecting lambs with highly developed early puberty characteristics. Spirulina (SP) has been evaluated as a natural product supplement to boost lamb growth, immunity, and productivity.
Aim:
Study growth performance, blood metabolites, puberty development traits, semen quality, and seminal plasma biochemical concentrations of growing Barki lambs when supplemented with SP at different levels.
Methods:
In a 24 weeks study, 30 Barki male lambs weighing an average of 21.78 ± 2.56 kg, with a body condition score of 3.20 ± 0.55 and an age of about 16 ± 0.24 weeks were used. The lambs were randomly assigned to three groups (10 lambs each) of daily Spirulina (SP) supplementation levels per lamb of 0 mL (control), 50 mL (SP1), and 100 mL (SP2). The SP powder was made into a water suspension using SP to water ratio of 1 g:10 ml. The growth characteristics, as well as the development of puberty, blood metabolites, and semen quality analysis of every lamb, were measured.
Results:
The growth performance was greater (p < 0.05) in SP2 lambs compared with other lambs. While daily dry matter intake was not affected by SP treatment, feed efficiency had significantly improved in SP2 groups. Furthermore, the SP2 lambs have attained puberty at early ages than control lambs. The testes volume of SP2 lambs was bigger (p < 0.05) than other groups throughout the pre-pubertal up to puberty stage. The addition of SP had no effects on the total protein, glucose, and triglycerides concentrations. Meanwhile, the cholesterol concentration was lowest (p < 0.05) in the SP2 lambs. The blood and seminal plasma levels of alanine aminotransferase and aspartate aminotransferase decreased (p < 0.05) in the SP lambs more than their control counterparts. The levels of superoxide dismutase reduced glutathione, and total antioxidants had increased (p < 0.05) in the treated lambs compared with the control group. Further, the malondialdehyde levels decreased (p < 0.05) in the SP-treated lambs. Additionally, the SP2 lambs produced better semen quality than the control lambs.
Conclusion:
SP supplementation (100 mL/head/day) enhanced growth performance, feed efficiency, and antioxidative status, exerting a positive influence on the physiological parameters and sexual behavioral patterns at puberty in Barki lambs.

Key words: Spirulina, Growth performance, Puberty, Semen quality, Barki lambs