Effect of photoperiod in the third trimester of gestation on milk production and circulating hormones in dairy goats

S. J. Mabjeesh*, O. Gal-Garber, A. Shamay

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

24 Scopus citations

Abstract

Multiparous Israeli Saanen goats (n = 8) were blocked at dry off (approximately 45 d prepartum) into 2 treatments of 4 goats each based on body weight (BW), previous milk production, and the number of detected embryos in utero. Treatments consisted of long-day (16 h light:8 h dark) and short-day (8 h light: 16 h dark) photoperiods at normothermic ambient temperature (22°C, 72% relative humidity). All goats were returned to ambient photoperiod after kidding, milked twice daily, and milk yield was automatically recorded. Dry matter intake was similar between treatments and averaged 980 g/d. Milk production was greater in the short-day than in the long-day treatment (2,932 vs. 2,320 g/d) during the 12-wk experimental period. Milk protein and lactose contents were similar in both treatments and averaged 3.61 and 4.88%, respectively, whereas milk fat was greater in the long-day treatment (4.80 vs. 4.22%). Plasma insulin-like growth factor 1 was greater in the long-day treatment (149 vs. 73 ng/ mL) during the dry period than in the short-day treatment, but was similar postkidding, averaging 76 ng/ mL. Concentrations of triiodothyronine in plasma were similar in both treatments during the dry period, but greater during lactation in the short-day treatment (122.1 vs. 94.1 ng/mL). Plasma prolactin was greater in the long-day than in the short-day treatment during the dry period (28.0 vs. 17.5 ng/mL), whereas it was similar throughout lactation (11.7 ng/mL). These data support the idea that greater milk production in goats exposed to short days during the dry period is not explained by differences in feed intake or increased secretion of insulin-like growth factor 1.

Original languageAmerican English
Pages (from-to)699-705
Number of pages7
JournalJournal of Dairy Science
Volume90
Issue number2
DOIs
StatePublished - Feb 2007

Bibliographical note

Funding Information:
This research was funded by the US-Israel Binational Agricultural Research and Development Fund (Award #US-3201-01).

Keywords

  • Dairy goat
  • Dry period
  • Photoperiod
  • Prolactin

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