Effect of the inclusion of lemon citrus pulp in the diet of Valle del Belice lactating ewes. Milk production and composition.

Abstract

Lemon citrus pulp residues from the citrus juice industry; it belongs to the citrus by-product that are more extensively used for livestock feeding. Furthermore, citrus pulp is a source of flavonoids such as hesperidin and naringin, which have antioxidant properties. This study aimed to investigate the effect of fresh lemon citrus pulp (LP) as natural antioxidant, on feeding behavior, milk yield and milk quality of Valle del Belice lactating ewes in the hot summer season in Sicily. A total of 15 second lambing ewes were individually allocated in 3¥3 m box and fed with 3 diets in a 3 ¥ 3 Latin square design, with 3 phases composed of 21 days. The diets were: LP0, mixed hay ad libitum plus 600 g/d of concentrate; LP1, mixed hay ad libitum plus 400 g/d of concentrate and 1 kg/d of LP; LP2, mixed hay ad libitum plus 200 g/d of concentrate and 2 kg/d of LP. The samples of offered and refused forage, concentrate and LP were analyzed for the determination of DM, CP, EE, ash, NDF, ADF and ADL. Individual milk samples were analyzed for lactose, fat, protein, casein, urea, SCC, pH, titratable acidity. At the end of the pre-experimental and experimental phases, total polyphenol intake, milk polyphenol content and milk antioxidant capacity were also determined. Statistical analyses were performed using the MIXED model where experimental phase (1, 2, 3) and diet (LP0, LP1, LP2) were fixed factors and the ewe was considered as random factor. On the basis of voluntary feed intake, the ewes of each group ingested the same dry matter, around 2 kg/d/head, but the LP2 group received lower net energy than other groups (1,27 vs. 1,33 UFL), in average slightly higher of their nutritional needs. The LP resulted 10% and 20% of the total DM intake, in LP1 and LP2 group respectively. The effect of the high temperatures determined average low milk productions. The LP2 ewes produced significantly lower daily milk yield than the other two groups (322 g/d vs. 369 g/d and 355 g/d for LP2, LP0 and LP1 groups respectively), probably due to lower net energy ingested. Milk fat did not differ significantly among groups, while milk protein and casein percentages showed higher values in LP2 than in LP1 group, probably due to higher availability of amino acids for the intestinal absorption. The milk urea content of LP0 resulted significantly lower than other groups. Polyphenol analyses are still under execution.