Category: Volume 69
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Effects of heat stress on performance of high yielding dairy Holstein cows in a hot-arid environment

H. DJELAILIA^1*

R. BOURAOUI²

T. NAJAR¹

¹ Laboratoire de Recherche : Matériaux Molécules et Applications, Institut National Agronomique de Tunisie, Université de Carthage, 43 Avenue Charles Nicolle, 1082 Tunis, Tunisie

² Ecole Supérieure d’Agriculture de Mateur, Université de Carthage, 7030 Mateur, Tunisie

Abstract - The aim of this work is to characterize the heat stress intensities level in the region of Sfax and to study its effects on physiological parameters: Respiratory rate, heart rate and Rectal temperature, using the temperature-humidity Index (THI). THI was calculated over a period of two months (August and September) from daily averages of ambient temperature and relative humidity. Physiological parameters were measured three times per day. A quantitative milk control was performed weekly from the quantities of milk produced. Statistical analyses of collected data were performed using SAS software. The results highlighted the existence of heat stress in the study area with average THI values ranging from 73 to 83.61, exceeding therefore the critical threshold of 72 established for the Holstein cow. The variation of THI value has led to an increase in rectal temperature, cardiac and respiratory frequencies of 1.7 ° C, 7 beats per min and 6 breaths per min, respectively. This stress has also caused a decrease in production from 28.31 to 25.8 kg per cow per day, hence the amount of milk dropped by 2.51 kg per cow per day. It was concluded that summer heat stress affects the physiological parameters and production performance of the Holstein dairy cow raised under in the arid climate of Tunisia.

Keywords: Milk production, Physiology, Heat Stress, THI, dairy cow.

Category: Volume 69
Hits: 2668

Evaluation of the protective power of cade and myrtle as natural preservatives of frying oil

Évaluation du pouvoir protecteur du cade et du myrte en tant que conservateurs naturels de l’huile de friture

C. HAFSI^1,2*

D. KRICHENE³

H. FALLEH⁴

M. BEN JEMAA⁴

H. BEN FRAJ³

R. KSOURI⁴

¹ Laboratoire des Plantes Extrêmophiles, Centre de Biotechnologie de BorjCédria (CBBC), BP 901, 2050 Hammam-Lif, Tunisie.

²Institut Supérieur de Biotechnologie de Béja, Université de Jendouba, Av Habib Bourguiba BP 382, 9000 Béja, Tunisie.

³Laboratoire de Biotechnologie de l'Olivier, Centre de Biotechnologie de BorjCédria (CBBC), BP 901, 2050 Hammam-Lif, Tunisie.

⁴ Laboratoire des Plantes Aromatiques et Médicinales, Centre de Biotechnologie de BorjCédria (CBBC), BP 901, 2050 Hammam-Lif, Tunisie.

Abstract -Vegetable oils are known for their health benefits. However, during a heat treatment, such as frying, several degradations can occur, in particular lipid peroxidation. However, this lipid degradation can be avoided through the use of powerful natural antioxidants such as phenolic compounds and essential oils. Thus, the first part of this work was devoted to a phytochemical study of phenolic compounds (two extractions: soxhlet and maceration) and essential oils of two aromatic plants (Myrtus communis and Juniperus oxycedrus) especially for their antioxidant activities. The second part revealed that the phenolic compounds of myrtle and cade have the potential to be used as natural preservatives of heat-treated edible oils.

Keywords: vegetable oils, lipid peroxidation, natural antioxidants, phenolic compounds, essential oils, natural preservative.

Category: Volume 69
Hits: 3963

Chemical Composition, Antioxidant and Antibacterial Activities of Pistacia lentiscus and Rosmarinus officinalis Essentials oils

Composition chimique, activités antioxydantes et antibactériennes des huiles essentielles de Pistacia lentiscus et Rosmarinus officinalis

H. SELMI^1*

A. DHIFALLAH¹

A. BAHRI²

S. JEDIDI¹

C. ABBES¹

H. ROUISSI²

¹ Sylvo-Pastoral Institute of Tabarka, University of Jendouba

² Higher Institute of Agriculture of Mateur, University of Carthage

Abstract - Tunisia is characterized by a climate that allows the proliferation of many plants rich in active substances with multiple biological activities and can replace the use of antioxidants and synthetic antibiotics.For this reason, the essential oils of Rosmarinus officinalis and Pistacialentiscuswere extracted with the technique of steam distillation, the chemical composition of the essential oils was analyzed by gas chromatography, and the antioxidant capacity was evaluated by the DPPH test and the antibacterial activity by the well method. Our results showed a significant difference (p <0.05) in the yield of essential oils. Indeed, we recorded a yield of 0.7% for R.officinalis against 0.07% for P. lentiscus. Both species have an important ability to trap free radicals but the essential oil of Pistacialentiscus has an antioxidant capacity superior to that of Rosmarinus officinalis oil. Likewise, for the antibacterial activity, the essential oils of Pistacia lentiscus were the most active against the bacterial strains tested except the Salmonella strain was more sensitive with Rosmarinus officinalis essential oil than Pistacia lentiscus essential oil. The results of the GC analysis -DM essential oils showed a complex and highly variability of chemical and aromatic composition for each species, the main components of the essential oil of P.lentiscus were monoterpenes: α-pinene (21,86- 17.87%), limonene (16.98-12.02%), whereas for R.officinalisessential oil were 1.8-cineole (28.58-38.12%) and camphor (12.81-9.65%).To conclude, the antioxidant power and the antibacterial activity are strongly correlated with the chemical composition of the essential oils.

Keywords: Essential oils, Chemical Composition, Antioxidant activities, Antibacterial activities, Rosmarinus officinalis, Pistacialentiscus.

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