Abstract
Twenty four Najdi ram lambs, weighing an average of 42.0+0.6 kg were utilized in this experiment to evaluate the effects of various alfalfa hay particle lengths in the diets and frequency of feeding on nutrients digestibility, ruminal retention time, total mean retention time and transit time. Lambs were randomly placed in a 3x2 factorial arrangement of three dietary treatments: 9.5 and 14 mm diets where alfalfa hay was processed to 9.5 and 14 mm particle lengths, respectively mixed with 3 parts of concentrate and pelleted as total mixed ration and long hay diet where one part of loose alfalfa hay (17.8 +/- 2.4 cm) was offered in combination with 3 parts of only-concentrate pellet and two feeding frequencies: once daily feeding at 0800 h and twice daily feeding in two equal portions at 0800 and 1500 h. All dietary treatments were homogeneous in their ingredient composition. Altering the particle length of alfalfa hay in diets did not affect the digestibility of DM or CP whereas digestibilities of ADF and NDF and ruminal retention time were 4.2 and 5.3% units higher (p<0.05) and 6.3 h longer (p<0.05), respectively for the long hay diet versus the 9.5 mm pelleted diet. The total mean retention time for the long hay diet was longer (p<0.05) at 63.1 h compared with the 9.5 and 14 mm diets. Lambs fed once a day had higher (p<0.05) NDF digestibility and 4.9 and 3.8 h longer (p<0.05) ruminal and total mean retention times, respectively than lambs fed twice daily. On the other hand, neither particle length of the alfalfa hay nor frequency of feeding had affected p>0.05) the lower tract retention time and transit time.