References of "Rouissi, Hamadi"
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See detailUse of Front-Face Fluorescence Spectroscopy to Differentiate Sheep Milks from Different Genotypes and Feeding Systems
Hammami, Moncef; Dridi, sami; Zaïdi, Fethi et al

in International Journal of Food Properties (2013), 16(Issue 6),

The objective of the present study was to assess the potential of front-face fluorescence spectroscopy coupled with chemometric tools for the evaluation of the quality of milk samples according to the ... [more ▼]

The objective of the present study was to assess the potential of front-face fluorescence spectroscopy coupled with chemometric tools for the evaluation of the quality of milk samples according to the feeding system and genotype. Fifty (n = 50) ewe's milk samples were scanned after excitation set at 250, 290, 322, and 380 nm and emission set at 410 nm. Thirty out of the 50 samples composed the first trial and were obtained from two different genotypes (i.e., Comisana versus Sicilo-Sarde); the second trial was composed of 20 samples obtained from the Sicilo-Sarde genotype with two different feeding systems in pen (soybean versus scotch bean). Milk samples were divided into four groups named Sicilo-Sarde with pasture feeding (Spas), Comisana with pasture feeding (Cpas), Sicilo-Sarde feeding on scotch bean (Ssco), and Sicilo-Sarde feeding on soybean (Ssoy). The factorial discriminant analysis was applied to the: (i) four groups (i.e., Spas, Ssco, Ssoy, and Cpas) and (ii) three groups composed only of Sicilo-Sarde genotype (i.e., Spas, Ssco, and Ssoy). Considering the four groups, the best result was obtained with the excitation vitamin A spectra since correct classification amounting to 76% was observed. When the factorial discriminant analysis was performed with the three groups belonging to the Sicilo-Sarde genotype, the best result was obtained again with vitamin A spectra (i.e., emission and excitation spectra) since 88.6% of correct classification was observed. Concatenation technique applied to the five fluorescence spectra improved the rate of classification between the four groups since 44 out of 50 samples were correctly classified. No misclassification was observed between milk samples collected from ewes with pasture feeding from the pen feeding. It was concluded from the obtained results that fluorescence spectroscopy could be considered as a powerful tool for differentiating between raw milks according to both genotype and feeding system. [less ▲]

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See detailMilk production of Holsteins under Mediterranean conditions: case of the Tunisian population
Ben Gara, Abderrahmen; Borni, Jemmali; Hammami, Hedi ULg et al

in Rekik, Boulbaba (Ed.) Milk Production (2012)

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See detailMid infrared and fluorescence spectroscopies coupled with factorial discriminant analysis technique to identify sheep milk from different feeding systems
Karoui, Romdhane; Hammami, Moncef; Rouissi, Hamadi et al

in Food Chemistry (2011), 127(2), 743-748

Mid infrared spectroscopy (MIR) combined with multivariate data analysis was used to discriminate between ewes milk samples according to their feeding systems (controls, ewes fed scotch bean and ewes fed ... [more ▼]

Mid infrared spectroscopy (MIR) combined with multivariate data analysis was used to discriminate between ewes milk samples according to their feeding systems (controls, ewes fed scotch bean and ewes fed soybean). The MIR spectra were scanned throughout the first 11 weeks of the lactation stage. When factorial discriminant analysis (FDA) with leave one-out cross-validation was applied, separately, to the three spectral regions in the MIR (i.e. 3000-2800, 1700-1500 and 1500-900 cm(-1)), the classification rate was not satisfactory. Therefore, the first principal component (PCs) scores (corresponding to 3, 10 and 10 for, respectively, the 3000-2800, 1700-1500 and 1500-900 cm(-1)) of the principal component analysis (PCA) extracted from each of the data sets were pooled (concatenated) into a single matrix and analysed by FDA. Correct classification amounting to 71.7% was obtained. Finally, the same procedure was applied to the MIR and fluorescence data sets and 98% of milk samples were found to be correctly classified. Milk samples belonging to control and soybean groups were 100% correctly classified. Regarding milk samples originating from the scotch bean group, only 2 out of 33 samples were misclassified. It was concluded that concatenation of the data sets collected from the two spectroscopic techniques is an efficient tool for authenticating milk samples according to their feeding systems, regardless of the lactation stage. (C) 2011 Published by Elsevier Ltd. [less ▲]

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See detailMilk production of imported heifers and Tunisian-born Holstein cows
Rekik, Boulbaba; Bouraoui, Rachid; Ben gara, Abderrahmen et al

in American-Eurasian Journal of Agronomy (2009), 1(3), 36-42

Test day (TD) records of milk, fat and protein yields and somatic cell scores (SCS) were studied in Holstein cows in Tunisia. There were 43114, 32923 and 24633 lactation records collected on first, second ... [more ▼]

Test day (TD) records of milk, fat and protein yields and somatic cell scores (SCS) were studied in Holstein cows in Tunisia. There were 43114, 32923 and 24633 lactation records collected on first, second and third parity cows between 1992 and 2004 in 182 herds. Records were of cows born in Tunisia (22000 cows) and those imported from Europe (10830 cows) and North America (850 cows). Variation of total days in milk (DIM) per lactation was studied in function of the herd, calving year x calving season interaction and the origin of the cow. Test-day records were analyzed using a linear model that included calving year x calving season and herd x test-day date interactions, calving season, calving year and origin of the cow. The effective length of lactation was affected by all factors included in the model (p< 0.0001) in all lactations. Test- day milk, protein and fat yields and TD SCS varied (p< 0.01) with management and climatic factors (calving year x calving season and herd x test-day date interactions and year and season of calving). A cow produced 18.8 kg, 0.61 kg and 0.58 kg of milk, fat and protein yields on a daily basis in all lactations, respectively. Average SCS was 2.8 in the three lactations. The origin of the cow was an important (p < 0.05) source of variation for DIM, yields and SCS in all lactations except for first lactation cell scores (p>0.05). Cows born in Tunisia seemed to perform better than imported cows in the first lactation while imported cows showed clearly better performances in later lactations. North American cows produced the highest yields and had the lowest SCS among all cows in the second and third lactations. Imported high producing cows seemed able to adjust to Tunisian management conditions following their first lactation. [less ▲]

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See detailOptimal age at first calving for improved milk yield and lengh of productive life in Tunisian Holstein cows
Ben Gara, Abderrahmen; Bouraoui, Rachid; Rekik, Boulbaba et al

in American-Eurasian Journal of Agronomy (2009), 2(3), 162-167

The effects of age at first calving on milk production and true herd life were studied in Tunisian Holstein cows. There were 33,407 first lactation records of cows born between 1987 and 2001 from 166 ... [more ▼]

The effects of age at first calving on milk production and true herd life were studied in Tunisian Holstein cows. There were 33,407 first lactation records of cows born between 1987 and 2001 from 166 herds. Firstly, age at first calving was analyzed using an animal model that included herd, calving year, herd-calving year interaction, calving month, and age of dam as fixed effects and the random additive genetic effect. Secondly, differences in first lactation and productive life milk yields and in true herd life were explained by age at first calving in addition to herd, year at first calving, herd-year at first calving interaction and month at first calving. A cow produced on the average 5669.8 kg milk (SD=1812 kg) during a 305-d first lactation period. The lifetime production of a cow was was 19,496.3 kg (SD=12,192 kg) during 3.3 lactations (SD=1.8 lactations). Coefficients of determination ranged from 14% for true herd life to 64% for first lactation milk yield. The mean of true herd life was 38.6 months (SD=24 months) and the mean age at first calving was 28.7 months (SD=3.4 months). Posterior mean of heritability of the age at first calving derived by a Markov Chain Monte Carlo Bayesien method via a Gibbs sampling algorithm was 0.08. The reduction of age at first calving to around 24 months may result in improved 305-d and lifetime yields and a longer herd life in Tunisian Holsteins. [less ▲]

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