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Titolo:
Photoperiodic entrainment of seasonal changes in the appetite, feeding behaviour, growth rate and pelage of pony colts
Autore:
Fuller, Z; Cox, JE; Argo, CM;
Indirizzi:
Liverpool John Moores Univ, Sch Biol & Earth Sci, Liverpool L3 3AF, Merseyside, England Liverpool John Moores Univ Liverpool Merseyside England L3 3AF e, England Univ Liverpool, Dept Vet Clin Sci & Anim Husb, Neston CH64 7TE, England Univ Liverpool Neston England CH64 7TE im Husb, Neston CH64 7TE, England
Titolo Testata:
ANIMAL SCIENCE
, volume: 72, anno: 2001,
parte:, 1
pagine: 65 - 74
SICI:
1357-7298(200102)72:<65:PEOSCI>2.0.ZU;2-4
Fonte:
ISI
Lingua:
ENG
Soggetto:
WHITE-TAILED DEER; GROWING HORSES; FOOD-INTAKE; AD-LIBITUM; METABOLISM; SHEEP; ENERGY; WINTER; MARES;
Keywords:
appetite; colts; growth; metabolic rate; seasonal variation;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Agriculture,Biology & Environmental Sciences
Citazioni:
27
Recensione:
Indirizzi per estratti:
Indirizzo: Argo, CM Liverpool John Moores Univ, Sch Biol & Earth Sci, Byrom St, Liverpool L3 3AF, Merseyside, England Liverpool John Moores Univ Byrom St Liverpool Merseyside England L3 3AF
Citazione:
Z. Fuller et al., "Photoperiodic entrainment of seasonal changes in the appetite, feeding behaviour, growth rate and pelage of pony colts", ANIM SCI, 72, 2001, pp. 65-74

Abstract

Relationships among photoperiod and changes in voluntary food intake, feeding behaviour growth and pelage were determined in seven, 2-year-old pony colts (182.4 (s.e. 5.4) kg). Individually housed colts were provided with adlibitum access to a complete pelleted diet (gross energy = 16.7 MJ/kg dry matter). Voluntary food intake (VFI, kg/day) was calculated daily and body weights were recorded weekly throughout the 36-week study. Feeding behaviour was evaluated at approximately 4-week intervals by continous observation (24 h), and the hair weight density (HWD, mg/cm(2)) of shoulder pelage was determined fortnightly. Day length was artificially manipulated to mimic the prevailing mid-summer photoperiod (16 h light : 8 h dark, 16L:8D). After 1 week of the study (and the preceding fortnight), day length was abruptly decreased and thereafter animals were exposed to alternating 14-week periods of short (SD, 8L:16D) and long days (LD, 16L:8D). The mean daily VFI of individual ponies was calculated weekly and normalized for digestible energy(DE) content and metabolic body weight (DEI, MJ/kg M-0.75). The average daily gain (ADG, kg/day) in body weight of each individual was calculated weekly. The apparent digestibility of dietary energy (digestibility) was determined over 72 h (no.=6) on two occasions (days 92 to 95 and 190 to 193) during the study. Digestibility was similar in both periods (0.48, s.e. 0.01). DEI, ADG and HWD changed in a cyclic manner throughout the study. the period of the appetite cycle (24.4 (s.e. 1.3) weeks) did not differ from that of the 28-week photoperiodic regime. DEI decreased from a maximum of 1.4 (s.e. 0.03) MJ/kg M-0.75 per day (day 21), to a nadir of 0.75 (s.e. 0.02) MJ/kg M-0.75 per day (day 154, (P<0.001) and had increased (P<0.001) to attain a second zenith (0.93 (s.e. 0.01) MJ/kg M-0.75 per day) before the end of the study. Ponies ate discrete meals of similar duration, but meal frequencywas associated with changes in VFI (r = 0.77) as was proportion of time spent feeding (r = 0.79). Changes in ADG reflected those of DEI. Body weight was stable for 4 weeks at the nadir of the appetite cycle. Maximal HWD was coincident with the nadir of the appetite and growth cycles. Regression of individual values for DEI on ADG described a linear relationship (R-2 = 0.80) which could be used to predict the energy requirements of growing poniesmaintained under similar conditions: DEItotal (MJ/kg M-0.75 per day) = 0.654ADG (kg/day) + 0.789The duration of the photoperiod appetite, growth and pelage cycles were similar, suggesting a causal relationship. Physiological responses to photoperiodic change were not immediate and exhibited a delay of 5 to 8 weeks.

ASDD Area Sistemi Dipartimentali e Documentali, Università di Bologna, Catalogo delle riviste ed altri periodici
Documento generato il 20/01/20 alle ore 23:13:31