An evaluation of Panicum maximum cv. Gatton: 1. The effect of stocking rate and period of absence on the production of sheep

The aim of this study was to evaluate the livestock production potential of Panicum maximum cv. Gatton cultivated under dry-land conditions and grazed at various stocking rates after various periods of re-growth. Treatments included a high stocking rate, fast rotation treatment (A), a medium stocking rate, medium rotation treatment (B) and a low stocking rate, long rotation treatment (C). The initial availability of dry matter differed between treatments and was lowest for treatment A and highest for treatment C. The same trend was observed for terminal availability of dry matter. The initial leaf:stem ratio did not differ between treatments A and B, but was lower for treatment C. The terminal ratio did not differ between treatments A and C but was higher for treatment B. Pasture height differed between treatments and was lowest for treatment A and highest for treatment C both at the beginning and end of the period. The sheep subject to treatment C had the highest average daily gain and there was no difference between treatments A and B. Although treatment B resulted in the best individual performance, the highest stocking rate yielded the highest livestock production per ha. (South African Journal of Animal Science, 2001, 31(2): 77-83

An evaluation of Panicum maximum cv. Gatton: 2. The influence of stage of maturity on diet selection, intake and rumen fermentation in sheep

The aim of the study was to evaluate the nutritional value of Panicum maximum cv. Gatton for sheep production in three different seasons and at three different stages of maturity. More mature pasture, compared to younger pasture, resulted in lower quality being selected. This was reflected in lower N values, lower digestibility and higher NDF, ADF and ADL values in selected material. Digestible organic matter intake (DOMI) also decreased with maturity. Grazing of more mature pasture resulted in lower rumen ammonia nitrogen (NH3-N) levels and higher acetic:propionic acid ratios. This trend was noted in all seasons. The nutritional value of the pasture in summer was high enough to meet at least the maintenance requirements of sheep in all stages of maturity evaluated. The nutritional value of the young and medium mature autumn pasture was also high enough to meet at least the maintenance requirements, but at the mature stage intake was too low. Intake in winter at all stages of maturity, was too low to meet the maintenance requirements of sheep. (South African Journal of Animal Science, 2001, 31(2): 85-92

An evaluation of Panicum maximum cv. Gatton: 3. The partial digestion by sheep of organic matter, nitrogen and neutral detergent fibre of herbage at three stages of maturity during summer, autumn or winter

The aim of this study was to quantify the partial digestion of organic matter (OM), nitrogen (N) and neutral detergent fibre (NDF) in sheep grazing Panicum maximum cv. Gatton pastures at three stages of pasture maturity during summer, autumn or winter. As pasture progressed from the young to the mature stage, OM digestibility decreased for all seasons, but OM disappearance in the rumen was unaffected. OM disappearance from the small intestine decreased with increasing pasture maturity during summer, and OM disappearance from the large intestine decreased with increasing pasture maturity during winter. N disappearance from the small intestine decreased with increasing pasture maturity during all seasons and N disappearance from the large intestine decreased with increasing pasture maturity in summer. Non ammonia nitrogen disappearance from the small intestine was decreased with increasing pasture maturity only for mature autumn pasture. Total tract N disappearance decreased with increasing pasture maturity during summer and autumn. NDF disappearance from the rumen decreased with increasing pasture maturity during autumn and winter, while NDF disappearance from the large intestine was unaffected. NDF disappearance from the total tract decreased with increasing pasture maturity during all seasons. It was concluded that P. maximum cv. Gatton pasture would best be utilized at the younger stages of development and that nutritional value would be higher in summer followed by younger autumn and winter pastures. (South African Journal of Animal Science, 2001, 31(2): 93-100

PAX5-driven subtypes of B-progenitor acute lymphoblastic leukemia

Recent genomic studies have identified chromosomal rearrangements defining new subtypes of B-progenitor acute lymphoblastic leukemia (B-ALL), however many cases lack a known initiating genetic alteration. Using integrated genomic analysis of 1,988 childhood and adult cases, we describe a revised taxonomy of B-ALL incorporating 23 subtypes defined by chromosomal rearrangements, sequence mutations or heterogeneous genomic alterations, many of which show marked variation in prevalence according to age. Two subtypes have frequent alterations of the B lymphoid transcription-factor gene PAX5. One, PAX5alt (7.4%), has diverse PAX5 alterations (rearrangements, intragenic amplifications or mutations); a second subtype is defined by PAX5 p.Pro80Arg and biallelic PAX5 alterations. We show that p.Pro80Arg impairs B lymphoid development and promotes the development of B-ALL with biallelic Pax5 alteration in vivo. These results demonstrate the utility of transcriptome sequencing to classify B-ALL and reinforce the central role of PAX5 as a checkpoint in B lymphoid maturation and leukemogenesis