Ill-trift of suckling lambs on lowland pastures in Iceland. I. General characteristics and animal performance

H÷fundur┌tgefandi┌tgßfußr┌tgßfusta­ur
Ëlafur Gu­mundssonB˙na­arfÚlag ═slands, BŠndaskˇlinn ß Hvanneyri, Rannsˇknastofnun landb˙na­arins, Rannsˇknast÷­ SkˇgrŠktar rÝkisins, Tilraunast÷­ hßskˇlans Ý meinafrŠ­i, Vei­imßlastofnun1988ReykjavÝk
Rit┴rgangurT÷lubla­Bls.
B˙vÝsindi159-68

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Frß vefstjˇra: Greinina Ý heild sinni er a­ finna Ý pdf-skjalinu hÚr a­ ofan

ABSTRACT

Suckling lambs of the Icelandic breed were grazed on a dry highland pasture and on a lowland bog during five summers. The weight gains were 16% lower on the lowland than on the highland pasture, resulting in average carcass weight of 11.6 kg on the lowland compared to 13.7 kg on the highland pasture. The difference between the two groups was highly significant (P<0.001). In contrast the grazing pressure on the lowland was approximately 0.72 ewes per tonne of dry herbage and on the highland 2.24 ewes per tonne. The total difference in performance was not adequately explained by parameters such as parasitic load, disease, digestibility of herbage or mineral deficiency. Therefore it is suggested, with reference to the literature, that the cause might be an interaction between a soil fungal flora and the rumen flora.

Key words: grazing, fungi, ill-thrift, lambs, sheep


YFIRLIT

Van■rif lamba ß lßglendisbeit ß ═slandi I. Almenn einkenni og ■rif lamba

Ůa­ hefur lengi veri­ ■ekkt hÚr ß landi a­ l÷mb ■rÝfast almennt verr ß sumarbeit ß lßglendismřrum en ß hßlendi. Svipu­ van■rif eru ■ekkt vÝ­a erlendis. Hversu mikill ■essi munur er hefur ekki veri­ vita­, nÚ heldur af hverju hann stafar. Samanbur­ur ß beit sau­fjßr var ■vÝ ger­ur Ý tilraunum ß Au­k˙luhei­i og Ý S÷lvholti Ý Flˇa. Samanbur­urinn stˇ­ Ý 5 ßr. Tilraunin ß Au­k˙luhei­i var ger­ Ý um 470 m hŠ­ yfir sjßvarmßli ß ■řf­um ■urrlendismˇa me­ mosa■embu, gr÷sum og smßrunnum. Tilraunin Ý S÷lvholti var Ý um 20 m hŠ­ yfir sjßvarmßli ß ■řf­ri fremur illa framrŠstri mřri.

L÷mbin ß Au­k˙luhei­i ■rifust betur (P<0,001) en l÷mbin Ý S÷lvholti. Ůessi munur kom betur fram Ý fall■unga (18%) en daglegum vexti (16%) vegna mikils munar Ý kj÷tprˇsentu. Ůrßtt fyrir a­ beitarßlagi­ var a­eins um 0, 72 Šr ß tonn grˇ­urs ß lßglendinu, en um 2,24 Šr ß tonn grˇ­urs ß hßlendinu, var fall■ungi a­ me­altali Ý tilraununum, ■egar b˙i­ var a­ lei­rÚtta fyrir lambafj÷lda ß hverja ß, 11,6 kg ß lßglendismřrinni og 13,7 kg ß hßlendismˇanum.

Ormasmit var svo til ekkert Ý tilrauninni enda fÚnu gefi­ ormalyf reglulega yfir sumari­. Ekki er heldur hŠgt a­ skřra muninn eing÷ngu ˙t frß mun Ý meltanleika e­a efnaeiginleikum beitargrˇ­ursins ■vÝ in vitro meltanleiki var minni a­ me­altali yfir sumari­ ß Au­k˙luhei­i heldur en Ý S÷lvholti. Prˇtein- og trÚnis■Šttir s.s. frumuveggur og ,,acid detergent fibre" voru aftur ß mˇti hŠrra hlutfall af grˇ­ri Ý S÷lvholti.

Erlendis hefur sřnt sig a­ jar­vegssveppir geta dregi­ ˙r starfsemi ÷rvera Ý v÷mbinni og ■annig dregi­ ˙r fˇ­urnřtingu. Leiddar eru lÝkur a­ ■vÝ a­ skřringanna ß lÚlegri ■rifum lamba ß lßglendismřrum heldur en ß hßlendi ß ═slandi geti veri­ a­ leita Ý minnkandi starfsemi vambarflˇrunnar vegna ßhrifa jar­vegssveppa.


INTRODUCTION

The Icelandic system of lamb production requires very rapid growth rates throughout the short growing season if an acceptable carcass is to be produced. This rate of growth is commonly achieved in the highlands or mountain ranges, where average live weight gains are often above 300 g per day. Most of the highlands are grazed as commons and are often fully stocked or overgrazed. Therefore there is an urgent need to intensify the grazing on the lowlands, especially on the extensive fertile but underutilized bogs. However, Pßlsson (1957) has shown that the performance of lambs on such bogland is relatively poor.

This result is supported by the experience of many farmers.

It was therefore important to try to establish this difference in the grazing performance of lambs on the highland pastures on the one hand and the lowland pastures on the other. Should such a difference be substantiated, further work was envisaged to attempt to delineate the factors involved in the ill-thrift.