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Effects of dietary supplements of zinc-methionine on milk production, udder health and zinc metabolism in dairy goats

Published online by Cambridge University Press:  17 February 2003

Ahmed AK Salama
Affiliation:
Unitat de Producció Animal, Departament de Ciència Animal dels Aliments, Universitat Autònoma de Barcelona, 08193 Bellaterra, Spain Present address: Sheep and Goat Research Department, Animal Production Research Institute, 4 Nadi El-Said, 12311 Dokki, Giza, Egypt.
Gerardo Caja
Affiliation:
Unitat de Producció Animal, Departament de Ciència Animal dels Aliments, Universitat Autònoma de Barcelona, 08193 Bellaterra, Spain
Elena Albanell
Affiliation:
Unitat de Producció Animal, Departament de Ciència Animal dels Aliments, Universitat Autònoma de Barcelona, 08193 Bellaterra, Spain
Xavier Such
Affiliation:
Unitat de Producció Animal, Departament de Ciència Animal dels Aliments, Universitat Autònoma de Barcelona, 08193 Bellaterra, Spain
Ramón Casals
Affiliation:
Unitat de Producció Animal, Departament de Ciència Animal dels Aliments, Universitat Autònoma de Barcelona, 08193 Bellaterra, Spain
Josefina Plaixats
Affiliation:
Unitat de Producció Animal, Departament de Ciència Animal dels Aliments, Universitat Autònoma de Barcelona, 08193 Bellaterra, Spain

Abstract

Twenty-two Murciano-Granadina dairy goats were used to investigate the effects of organic Zn supplementation of a diet containing a high level of inorganic Zn. Goats were kept in pens, machine milked once a day throughout lactation and fed a diet based on a dehydrated mixture of whole-plant maize and alfalfa ad libitum, alfalfa pellets, barley grain and a concentrate mixture. Treatments were: (1) control, and (2) supplemented with 1 g/d Zn-Methionine (Zn-Met) included in the concentrate mixture. After parturition, goats were blocked in week 3 and dietary treatments were applied until week 23. From weeks 3–20, feed intake, milk yield, milk composition, milk somatic cell count (SCC), and udder health were measured. In week 21, all goats were injected intraperitoneally with 1 g/d DL-methionine for 5 d to establish the effects of methionine under the conditions of udder stress induced by hand milking on the second day. During weeks 22 and 23, diet digestibility, and N and Zn balance were determined. Dry matter intake, milk yield, and milk contents of total solids, fat, total and true protein, and casein did not differ between treatments, but whey protein and non-protein nitrogen contents were significantly lower for the Zn-Met group. Milk SCC tended to decrease as a result of Zn-Met supplementation but differences between treatments were not significant when halves with persistent infection were excluded. Hand milking increased SCC in both groups, but udders of supplemented goats showed a lower reaction. Apparent absorption of N significantly increased and Zn retention tended to increase in Zn-Met supplemented goats. We conclude that Zn-Met supplementation can enhance resistance to udder stress in dairy goats. Effects were attributed to the organic Zn and not to the methionine component. Zn retention and protein utilization were also improved by the Zn-Met supplement.

Type
Research Article
Copyright
Proprietors of Journal of Dairy Research 2003

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