Abstract:The detergent system of analysis partitions lignin into two fractions : acid detergent lignin (ADL), usually equated with forage lignin, and 'acid detergent dispersible lignin' (ADDL), the existence of which has scarcely been recognised, but can be higher than ADL in tropical grasses. For nine species ADL and ADDL as percentage of original dry matter were, respectively: Aristida calcyna, 8.9 and 9.8; Astrebla squarrosa, 8.6 and 14.7; Chloris gayana, 3.9 and 6.7; Eragrostis sp, 4 3 and 8.8; Heteropogon contortus, 3.9 and 10.4; Iseilema membranaceum, 7.2 and 8.2; Panicum maximum, 1.8 and 5.7; Themeda triandra, 7.3 and 8.2; Sorghum sp, 3.4 and 13.8. Tropical legumes (four species) had much lower levels of ADDL. Azo-stained fibre showed that most of the free phenolic functions and the alkali-soluble lignin were in the ADDL fraction. The difference between grasses and legumes was so marked that azo-staining may provide a method for distinguishing grass and legume particles in feed or faecal samples. The apparent discrepancies between grasses and legumes in the effect of lignin on digestibility may be explained by the grass lignin having been grossly underestimated as ADL. When Heteropogon contortus and Astrebla squarrosa were incubated in dacron bags in the rumen the ratio of ADDL to ADL in the residual fibre decreased markedly in the first 48 h, indicating a higher apparent digestibility for ADDL. From feeding experiments with sheep the apparent digestibility of ADL and ADDL were 18 and 38% for Astrebla squarrosa and 14 and 26% for Stylosanthes hamata. As isolated lignin corresponding to ADDL was inhibitory in uitro to a mixed rumen microbial population at a concentration of 0.12 mg m1-l. Measurement of ADDL could easily be included in fibre analysis by the sequential detergent method as it would require only UV absorbance measurement on the acid detergent filtrate. This would allow measurement of total lignin within the existing system.

Abstract. Data from 2833 unmulesed Merino lambs from 49 sires and 1535 dams that were born from 2005 to 2009, were used to identify indicator traits for breech strike in a Mediterranean environment. Sheep were managed in a normal production environment where no preventative treatments were applied to protect them from being struck by flies, but were immediately treated when found to be fly struck. Seventy-seven skin, body conformation, wool, disease and production traits that may contribute to breech strike and that could qualify as potential indicator traits were recorded on progeny at birth, weaning, postweaning, yearling, spring and at pre-and post-hogget age at~18 months of age. In all, 31% of ewes and 22% of rams were fly struck in the breech area between birth and hogget shearing. The heritability of and the phenotypic and genetic correlations between the potential indicator traits and breech strike were estimated. The results showed that breech strike is a heritable trait (h 2 = 0.51 AE 0.10), and that the most important indicator traits for breech strike were dags, scored at any time, especially at hogget age (r g = 0.81 AE 0.15), spring (r g = 0.77 AE 0.13) or at weaning (r g = 0.64 AE 0.00), urine stain scored at weaning (r g = 0.54 AE 0.13) and marking (r g = 0.51 AE 0.15), neck wrinkle at hogget age (r g = 0.46 AE 0.13) and breech cover (r g = 0.32 AE 0.15) scored at post-weaning shearing. These traits could be used to select indirectly for breech strike resistance in a Mediterranean environment.

S U M M A R YFour swamp buffaloes (Bubalus bubalis) and four crossbred Bos indicus x B. taurus cattle, fistulated at the rumen and abomasum or duodenum, were offered rice straw with mineral supplements in two experiments. In Expt 1, the straw was supplemented with 5% of leaf of Leucaena leucocephala, and in Expt 2 with either urea or urea with sunflower meal and rice grain. Intake of supplements of urea or urea/sunflower/rice respectively was 935 and 681 g/kg offered in buffaloes and 566 and 789 in cattle.Buffaloes ruminated longer than cattle (Expt 1, 635 v. 452 min/day; Expt 2, 626 v. 466 min/day, P < 001). In Expt 1, voluntary intake and frequency of ' A ' sequence forestomach contractions of both species was not affected by species, but buffaloes had a greater (P < 005) contraction force in the rumen and omasum, lower rate o f ' B ' sequence rumen contractions, and faster (P < 0001) rate of gastrointestinal passage than cattle. In Expt 2, voluntary intake of both species was similar, and addition of concentrates did not affect voluntary roughage consumption, nor in situ rate of digestion of rice straw. Rate and predicted extent of digestion of dietary materials did not differ between species in Expt 1, despite lower concentrations of ammonia in rumen fluid in cattle than buffaloes; however in Expt 2, the rate of digestion of rice straw was higher (/> < 005) and predicted extent of digestion was 14-20% (P < 005) lower in buffaloes. Digestibility of cell wall constituents was lower (P < 005) in buffaloes than in cattle in both experiments, but in Expt 2, provision of concentrates reduced (P < 001) the proportion of digestible cell wall constituents digested in the forestomach of buffaloes, but not of cattle. Plasma urea concentrations were higher (P < 0-05) and transfer of urea to the rumen tended to be higher (7-4 v. 3-7gN/day; P<0-l0) in buffaloes. Faster fractional outflow rates of microbes and of small digesta particles from the rumen were observed in buffaloes in Expt 1.In Expt 1, more microbial N left the abomasum (35 v. 30 g per kg organic matter apparently digested in the forestomach; P < 005) of buffaloes than cattle, and in Expt 2 more non-ammonia N (43 v. 31 g per kg organic matter apparently digested in the forestomach) flowed into the intestines of buffaloes. In Expt 1 microbial retention time was shorter (26 v. 47 h; P < 001) in the rumen of buffaloes.Patterns of appearance of plastic particles with time after dosing indicated faster escape from the rumen of buffaloes of non-chewed particles, and a greater proportion of particles subjected to ruminative chewing, than in cattle. Ruminative chewing of plastic particles in buffaloes was progressively more efficient than in cattle with increasing particle length and decreasing specific gravity. Analysis of faecal particle distribution indicated buffaloes tended to excrete smaller particles than cattle.The adaptive significance of faster digesta passage in the buffaloes appeared to derive from a more balanced supply of absorbed protein relative to dige...

The aim of the experiments reported was to evaluate the protection from microbial breakdown of two methionine formulations (Lactet and Mepron) and to measure responses in wool production, liveweight, amino acids and glutathione in blood and tissues when one of these forms of methionine (Lactet) was supplied to merino wethers fed at maintenance. Lactet was well protected against microbial breakdown in the rumen. Peak values for concentrations of methionine in plasma, following administration of the different forms of methionine into the rumen, were 574, 148 and 143pmol L-1 for Lactet, DL-methionine and Mepron. Production responses to dosed levels of Lactet (0, 1, 2, 3, 5, 8 g methionine dayw1) were measured over 63 days in the animal house. Significant linear responses were obtained for wool growth (4-38%), fibre diameter (0.5-2 8m) and liveweight gain (30-1 15%). Concentrations of reduced glutathione in blood, liver and skin were increased, at some times during the experiment, by provision of Lactet. However, responses were inconsistent and highly variable among sheep, Glutathione was of limited use as an indicator of sulfur amino acid intake or status. Sulfate in plasma increased markedly at all levels of Lactet intake, and there was a linear relationship between Lactet intake and the concentration of sulfur in wool. Plasma free methionine and the ratio of methionine to total essential amino acids showed significant linear responses to the supplements. It was concluded that Lactet was an effective method of supplying rumen-protected methionine to ruminants.