A Comparative Study of Sheep Breeds: Fattening Performance, Carcass Characteristics, Meat Chemical Composition and Quality Attributes.

Fattening performance, Carcass characteristics, chemical composition, and meat quality were evaluated in three sheep breeds: Awassi, Harri, and Najdi. Forty-five lambs of similar weight and age were raised for 90 days under similar conditions. The Harri and Najdi breeds had higher dressing-out percentages than Awassi sheep. The Awassi and Harri breeds had thicker backfat than the Najdi breed. No significant difference was found in moisture, protein, and intramuscular fat among the breeds. However, the Harri breed had a higher ash content than the Awassi and Najdi breeds. The Najdi breed had higher ultimate pH and lower cooking loss than the Awassi and Harri breeds. Awassi and Harri sheep had a higher myofibril fragmentation index, longer sarcomere length, and lower hardness and chewiness than Najdi sheep. Subjectively, no significant differences were detected between the breeds, except for flavor intensity while the Awassi sheep were rated in between and not significantly different. In conclusion, breed affected carcass characteristics, meat composition, and the quality of sheep. The dressing yield was higher in Harri and Najdi than Awassi sheep. Awassi sheep showed superior meat quality characteristics followed by Harri sheep. However, Najdi sheep had the best cooking loss percentage and flavor intensity score.

Subsequent influences of feeding intact green seaweed Ulva lactuca to growing lambs on the seminal and testicular characteristics in rams.

The present experiment was designed to investigate the subsequent influences of supplementing different levels of intact green seaweed Ulva lactuca (0%, 3%, and 5% DM) to growing sexually immature lambs during the growth period (74 d) on the seminal and testicular characteristics of sexually mature rams. Ulva lactuca was manually collected, adequately prepared, and then incorporated into lambs' diets. Eighteen male 3-mo-old lambs of the Awassi breed with a mean BW of 22.57 kg (SD = 1.08) were randomly assigned into treatments. The obtained results indicate that offering Ulva lactuca at the level of 3% or 5% DM to lambs during the growth period had no subsequent impacts (P > 0.05) on liver and kidney functions as well as blood water balance in rams, thereby suggesting that Ulva lactuca can be safely supplemented to lambs during growing. However, our findings point out that feeding a lamb diet supplemented with intact Ulva lactuca failed to demonstrate any subsequent benefit (P > 0.05) on the growth performance, thermoregulatory responses, and plasma oxidative status in rams. Above all, it was clearly evident that supplementing intact Ulva lactuca to lambs had demonstrated subsequent negative influences (P < 0.05) on seminal and testicular characteristics of rams, more noticeably observed at the 5% DM inclusion rate than at 3%. These results were manifested by the inferior (P < 0.05) seminal quality, reduced (P < 0.05) testicular morphometry, changes (P < 0.05) in testicular histopathology, defective (P < 0.05) endocrine signaling, and increased (P < 0.05) seminal oxidative stress in rams fed diets supplemented with Ulva lactuca during the growth period compared to control rams. The deleterious impacts of feeding intact Ulva lactuca on spermatogenesis and germ cell loss were proven to be attributed to the dysfunction of Sertoli cells. Collectively, these results provide novel insights on the subsequent influences of dietary supplementation of intact Ulva lactuca to lambs. The consistent evidence of profound negative impacts on seminal and testicular characteristics as well as the resulting data of no improvement of subsequent growth, thermoregulation, and plasma oxidative status in rams prompts us to tentatively recommend the avoidance of feeding intact Ulva lactuca to lambs.

In vitro metabolism of the stereoisomers of 2,6-diaminopimelic acid by mixed rumen protozoa and bacteria.

Formation of lysine from stereoisomers (SI) of 2,6-diaminopimelic acid (DAP) and the epimerization between the three SI of DAP (DAP-SI) by rumen protozoa and bacteria were examined. Mixed rumen protozoa (P) and bacteria (B) were isolated from the rumen of goats given a concentrate and hay cubes and incubated separately with and without a mixture and a single one of the three DAP-SI. In P suspensions, mixed DAP-SI decreased by 10.59% as a whole and converted mainly to lysine by 8.41% during 12 h incubation. When meso-, L- and D-DAP were added singly to the media, the results showed that each DAP-SI interconverted and produced lysine. This means that mixed rumen protozoa have an ability to synthesize lysine from not only meso-DAP but also from D- and L-DAP, though probably via meso-DAP, and hence have DAP epimerase activities for the reversal conversion of each DAP-SI. This is the first discovery to show the interconversion of DAP-SI and synthesis of lysine from them by protozoa. In B suspensions, mixed DAP-SI decreased by 10.92% as a whole and converted to lysine by 4.20% during 12 h incubation. When a single DAP-SI was added to the media, meso-, L- and D-DAP were interconverted and then converted to lysine by the rumen bacteria as well as the protozoa. This also means that mixed rumen bacteria have DAP epimerase activities to interconvert DAP-SI and have an ability to synthesize lysine from not only meso-DAP but also from L- and D-DAP, and this is also the first finding in rumen bacteria.

Measurement of total and separate stereoisomers of diaminopimelic acid in rumen bacteria by high-performance liquid chromatography.

New high-performance liquid chromatographies were examined and applied for the analyses of the total (with one peak) and separate three stereoisomers of 2,6-diaminopimelic acid (DAP) in hydrolysed mixed rumen bacteria. The methods start with the reaction of DAP with 1-fluoro-2,4-dinitrophenylalanine amide for derivatisation. A mixture of 0.05 M triethylamine phosphate (pH 3.0) and acetonitrile (72:28, v/v) was used as an isocratic mobile phase for the total DAP determination (method 1), and a mixture of both solutions (78.5:21.5, v/v) for the determination of the separate three stereoisomers of DAP (method 2). The flow-rate was 1 ml/min; column, Merck LiChrospher 100 RP-18 (250 x 4 mm I.D.) of 5 microns particle size; column temperature, 40 degrees C; wavelength of detector, 325 nm. The retention times were 17.5 min for total DAP (method 1), and 39.4, 63.1 and 77.7 for meso-, LL- and DD-DAP, respectively (method 2). Lysine can also be determined by method 2 and the retention time was 122.8 min. The minimum detectable limit was 2.5 microM. The average analytical recoveries were 98.6% for total DAP and 99.1%, 100.4% and 100.2% for meso-, LL- and DD-DAP, respectively. The content of total DAP of the hydrolysed rumen bacteria collected from three goats fed lucerne cube and concentrate ranged from 25.55 to 27.36 mumol/g bacterial DM (method 1). The contents of the separate stereoisomers of DAP in the hydrolysed rumen bacteria from the three goats ranged from 19.64 to 22.06 and from 4.98 to 5.21 mumol/g bacterial DM for meso- and LL-DAP, respectively (method 2). DD-DAP was not detected.