title: Influence of phased inclusion of halofuginone on broiler skin tensile strength and growth performance.
abstract: The effect of continuous administration, weekly 24 h administration, phased withdrawal and phased inclusion of dietary halofuginone at 3 mg kg-1 on skin tensile strength was tested in Ross I broiler pullets. Controls received monensin continuously at 100 mg kg-1. A total of 2,592 birds were used in 2 lots of 1,296 in 2 separate programmes. Continuous dietary administration of halofuginone affected skin tensile strength negatively (P less than 0.05), with an equally significant recovery following a 7 d withdrawal period. A polynomial regression analysis indicates that skin strength may undergo a slight compensatory overstrengthening reaction within 7 d of withdrawal of halofuginone. Weekly 24 h administration of halofuginone reduced differences in skin strength between treatment and controls to non-significant levels. Differences in skin strengths between controls and the halofuginone phased inclusion programme decreased as the birds aged, being significant (P less than 0.05) on Days 14 and 28 and non-significant on Days 21, 35, 42 and 49. A weakening of skin tensile strength of broiler carcasses, as far as it may be influenced by halofuginone, can be alleviated through different shuttle programmes involving halofuginone. Such programmes would include intermittent dosing, a withdrawal period, administration to older birds or a combination of these programmes.
authors.affiliation: Department of Livestock Science, Faculty of Agriculture, University of Pretoria, Republic of South Africa.
authors.forename: R I
authors.initials: RI
authors.lastname: Crosley
authors.forename: N H
authors.initials: NH
authors.lastname: Casey
authors.forename: G A
authors.initials: GA
authors.lastname: Smith
authors.forename: B
authors.initials: B
authors.lastname: Roosendaal
mesh_terms: D000818:Animals; D002645:Chickens / Q000254:growth & development / Q000502:physiology*; D003049:Coccidiostats / Q000008:administration & dosage*; D010880:Piperidines; D011799:Quinazolines / Q000008:administration & dosage*; D052999:Quinazolinones; D012867:Skin / Q000187:drug effects*; D012879:Skin Physiological Phenomena; D013718:Tensile Strength / Q000187:drug effects
chemical_list: D003049:Coccidiostats; D010880:Piperidines; D011799:Quinazolines; D052999:Quinazolinones; C010176:halofuginone