African Journal of
Agricultural Research

  • Abbreviation: Afr. J. Agric. Res.
  • Language: English
  • ISSN: 1991-637X
  • DOI: 10.5897/AJAR
  • Start Year: 2006
  • Published Articles: 6666

Full Length Research Paper

Effect of stocking rate on biomass variation and lamb performances for barley stubble in Tunisian semi arid region and under conservation agriculture conditions

Nizar MOUJAHED
  • Nizar MOUJAHED
  • LRGAA, Institut National Agronomique de Tunisie, 43 AV. Ch. Nicolle, 1082, Tunis, Tunisia.
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Sourour ABIDI
  • Sourour ABIDI
  • Institute National de Recherche Agronomique de Tunisie, Rue HédiKarray 2049 Ariana, Tunisia.
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Salah BEN YOUSSEF
  • Salah BEN YOUSSEF
  • Institute National de Recherche Agronomique de Tunisie, Rue HédiKarray 2049 Ariana, Tunisia.
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Cyrine DAREJ
  • Cyrine DAREJ
  • LRGAA, Institut National Agronomique de Tunisie, 43 AV. Ch. Nicolle, 1082, Tunis, Tunisia.
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Mohamed CHAKROUN
  • Mohamed CHAKROUN
  • Institute National de Recherche Agronomique de Tunisie, Rue HédiKarray 2049 Ariana, Tunisia.
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Hichem BEN SALEM
  • Hichem BEN SALEM
  • ICARDA Bldg No. 15, Khalid Abu Dalbouh St. Abdoun. P. O. Box 950764, Amman 11195, Jordan.
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  •  Received: 17 September 2015
  •  Accepted: 15 October 2015
  •  Published: 10 December 2015

Abstract

The integration of livestock in the practices of conservation agriculture (CA) was assessed in Tunisian semi-arid conditions. Forty five Barbarine lambs (aged 220 ± 10 days, average body weight 20 ± 2.5 kg) were used in a performance trial, carried out in the experimental station of INRAT. During the experiment, lambs were grazing on a plot of barley stubble cultivated according to CA was divided into 6 fenced equal subplots and to each subplot was assigned a stocking rate of animals (15 and 30 lambs per hectare, SR15 and SR30 respectively). The biomass of stubble and its botanical composition were estimated 2 times, using quadrats sampling technique. Live weight was determined 3 times after the start of the experiment (three 15-days successive periods) to calculate live weight gain (LWG) and daily live weight gain (DLWG). The amount of biomass varied (P <0.05) from 2204 to 2067 kg DM / ha for SR15 plots and from 2404 to 1826.5 kg DM/ha for SR30 ones. This decrease was higher with SR30 (P<0.05). Heads proportion decreased first, then leaves and finally stems. Biomass chemical composition declined with sampling period. During the first grazing period, lambs assigned to both treatments lost LW (P<0.001), mainly SR30 lambs as compared to SR15 (P<0.05, -610 and -110 g, respectively). The same trend was observed in DLWG (P<0.05). In the second period, the two groups exhibited similar LWG (about 2 kg) and DLWG (about 171 g/d). In the third period, SR15 lambs maintained their body weight, while SR30 group lost (P<0.001) about 400 g comparatively to the second period. It was concluded that under the studied feeding system, stubble grazing without supplementation allowed Barbarine sheep to maintain body conditions.

Key words: Lambs, barley stubble, stocking rate, conservation agriculture.