ILL-THRIFT TRIALS AT WINCHMORE

Press, Volume XCVIII, Issue 28890, 9 May 1959, Page 9

ILL-THRIFT TRIALS AT WINCHMORE

No Concrete Results In Two Seasons

In the last two seasons about 800 lambs receiving some 20 different treatments have been used in lamb ill-thrift trials at the Winchmore Irrigation Research Station. Reviewing these trials the station superintendent, Mr G. K. McPherson, says that in the 1957-58 season there was no marked response to any treatment and figures secured during trials in the present season indicated a similar trend. “In other words in some 20 trials involving 800 lambs in all in not one single case has the treatment applied had the effect of increasing substantially the growth rate of the lambs,” he states.

“These have been exploratory trials of a preliminary nature and it is obvious that they require repeating for several years to come. That they have failed to yield concrete results merely emphasises how complicated the ill-thrift picture is and how necessary it is to continue and expand the work into a problem which is of vital concern to many farmers in Canterbury.

In many cases the trials at Winchmore have begun with the birth of the lambs in the spring and have continued right through until late in the following autumn. Other trials have begun with the weaning of the lambs in December. The system followed has been to weigh the lambs at the beginning of the trials and carry out regular weighings at either weekly or fortnightly intervals from then onwards. As each lamb on the trial is tagged and numbered the individual growth rate at weekly or fortnightly intervals of some 800 lambs has been obtained.

Treatments so far have included a comparision of long versus short feed whilst the effect on the growth rate of treating the lambs with copper, cobalt, fine particle Phenothiazine, Frantin (bephenium embonate), selenium and some combinations of the above have been studied. The effect of varying levels of nitrate nitrogen in the herbage on the growth rate of lambs is also being investigated. Treatments have been carried out on both dryland and on irrigated pasture.

In the 1956-57 season when lamb ill-thrift was prevalent throughout Canterbury a survey made by officers of the Economic Section, Department of Agriculture, Christchurch, indicated that deaths from ill-thrift were more prevalent on rank feed, than on short, closely grazed pasture, states Mr McPherson? Experience on the station in that season indicated a similar trend. However, trials conducted over the last two seasons have not confirmed that view. The effect’ of height of growth on the thrift of lambs has now been investigated, in six trials. Growth has been controlled both by the use of the farm mower and by stocking. Controlled feed has been about one to two inches in height in some trials and mower height in others, whilst the uncontrolled feed has also varied in the different trials, ranging from three to six inches in some up to almost 12 inches in height in others. “Summed up there was no suggestion in the trials that long or short feed influenced the incidence of ill-thrift or affected markedly the liveweight gains of the lambs,” he said.

In the 1957-58 season by irrigating to maintain rapidly growing soft feed, ill-thrift was induced in one trial; but the length of feed had no influence on the extent of the outbreak. Death rates were about 20 per cent, on both controlled and uncontrolled pasture. This season similar treatments have failed to produce ill-thrift. It is of interest to record that of 1700 lambs drafted for the works this season from the station, the best draft has been a line of 111 Southdown cross lambs drafted early in April, which averaged 36.671 b with only one lamb graded second. These lambs from weaning onwards were set stocked on pasture consisting mainly of red and white clover some four to five inches in height. During dry weather this growth had been regularly irrigated at fortnightly intervals—in other words it closely resembled a treatment which in the previous season had induced ill-thrift.

Copper, given in the form of copper glycinate has been investigated in one trial only. There was no response to the copper treatment, and five livers from untreated lambs submitted for copper analyses were found to be normal.

In four trials cobalt was admin-

istered to the lambs in the form of a cobalt bullet. In some instances a slight response to cobalt was obtained; but in no case was the response spectacular or even marked. A similar position existed where lambs received both cobalt and copper.

Frantin (Bepfyenium Embonate) This substance, which has been develope'd for the control of nemotadirus infestation, was used for the first time in a trial during the present autumn. A total of 11 weekly weighings have been carried out since the lambs were drenched; but indications are that the response is unlikely to be marked. It is generally recognised, however, that nemotadirus is more likely to be a factor in lamb illthrift in the spring.

Fine Partcle Phenothiazine— Phenothiazine was included in one trial during 1957-58 and gave a small but significant response. It has also been one of the treatments used ih three trials this season. Although at times during the course of some trials there has been an indication that the lambs were responding to phenothiazine, the responses to drenching up to the present, as indicated by liveweight gains has been very slight. Selenium

Three groups of lambs totalling 136 in all are involved in trials with selenium. Weighings made so far indicate that the lambs drenched with selenium are unlikely to even show a slight response to the treatment. A comparison is also being made between lambs drenched with selenium and lambs receiving both selenium and cobalt. No weight differences are apparent between these two groups of lambs.

Nitratee Nitrogen— It has been suggested that high levels of nitrate nitrogen or alternatively fluctuating levels of nitrate nitrogen in the herbage might be a factor in lamb ill-thrift. In an attempt to produce this condition artificially, areas this season were topdressed at intervals with a nitrogenous fertiliser, a total quantity of 8 cwt. per acre being applied over a three-monthly period. Lambs grazing this pasture were compared with lambs grazing a pasture where no nitrogen had been applied. “The result of this trial could be summed up by saying that at no time on the area topdressed with the nitrogenous fertiliser did the nitrate nitrogen level of herbage reach a stage where it might be considered dangerous as a lamb feed,” states Mr McPherson. “Actually in the trial the lambs on the area topdressed with nitrogen have gained weight at a slightly higher rate than the control lambs, due possibly to there being more attractive feed on this area. The growth on the untopdressed plots of this trial had a distinctly yellow and unthrifty appearance. “The soil type on the Winchmore irrigation research station is the Lismore stony silt loam. There are extensive areas of this soil type on which it is reported that severe cases of ill-thrift in lambs have occurred. From these aspects the station could be considered an ideal area on which to conduct the trials.

“It could be that the very slight responses obtained to many of the treatments used at Winchmore is due to the fact that, in general, progress of the lambs as a whole on most of the trials has been fairly good. In the trials beginning with the birth of

the lambs in the spring (e.g. Romney cross lambs have been used) and in the marjority of cases these lambs have weighed 701 b or more at weaning. These relatively high weight gains have been disappointing as in many cases the lambs had been subjected to treatments which were considered might be ideal for the development of ill-thrift. “In some trials, however, moderate lambs only (50-601 b weight at weaning) have been used—lambs which have obviously not made good progress. Even when working with this class of lamb, compared with control lambs, the responses to the various treatments used has been small.”