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

Abstract

The influence of photoperiod manipulation in the dry period was examined in dairy goats experiencing environmental heat stress. Multiparous Israeli Saanen goats were blocked at dry off (∼60 d prepartum) into 2 groups of 4 goats each based on body weight, previous milk production, and detected embryo number. Treatments consisted of long-day (16 h light:8 h dark) and short-day (8 h light:16 h dark) photoperiods (LDPP and SDPP, respectively). Heat-stress conditions were applied by manipulating the environment of metabolic rooms to reach a maximum temperature of 37°C between 1000 and 2200 h, and a minimum of 23°C and 70.3% relative humidity. All goats were returned to ambient photoperiod after kidding, milked twice daily, and milk yield was automatically recorded. Dry matter intake during the dry period was similar between treatments, averaging 1,114 g/d. Milk production was significantly higher in the SDPP than the LDPP group (2,172 vs. 1,550 g/d) during the 12-wk experimental period. Milk protein and fat contents were similar in both groups and averaged 3.63 and 4.34%, respectively, whereas milk lactose was higher in the LDPP group (4.77 vs. 4.67%). Heart rates were similar between treatments and averaged 112.6 beats per minute (BPM). Respiration rates were lower in the morning (58.4 BPM) compared with the afternoon (91.2 BPM) and were not influenced by photoperiod. Rectal temperature was higher for the LDPP than the SDPP group (40.4 vs. 39.6°C). The thyroid hormone level (mean ± SE) was similar in both groups during the dry period, but higher during lactation in the LDPP goats up to 40 d postpartum (110±6.59 vs. 156±8.76 ng/mL). Plasma IGF-1 (mean ± SE) was higher in the LDPP group (279±62 vs. 162±27 ng/mL in SDPP) during the dry period but was similar postkidding, averaging 132±24 ng/mL. Plasma prolactin level (mean ± SE) was higher in the LDPP than the SDPP group during the dry period (17.2±1.6 vs. 10.6±0.99 ng/mL), whereas it was similar throughout lactation (0.61±0.28 ng/mL). These data support the idea that SDPP manipulation during heat load in dry goats can be used as an abatement strategy to reduce the carryover effect of heat stress observed during the subsequent lactation. The higher milk production in SDPP goats is explained by changes in circulating prolactin profile rather than differences in feed intake or secretion of insulin-like growth factor 1.

Mammary core clock gene expression is impacted by photoperiod exposure during the dry period in goats

“…Prolactin (PRL) is a potent lactogen and stimulates homeorhetic and mammary specific processes for adaptation to lactation. Circulating PRL levels are increased in ruminants exposed to LDPP (16 h of light and 8 h of dark) (Mabjeesh et al 2007;Dahl et al 2012;Mabjeesh et al 2013), and this hormonal change is hypothesized to mediate the homeorhetic response to changes in photoperiod (Dahl 2008). Our previous studies using a mouse mammary epithelial cell line showed that PRL functions as an input to the mammary clock as treatment with PRL significantly increased ARNTL expression levels, and timing of application shifted phase of expression (Casey TM et al 2014).…”

“…PRL was measured using a sandwich ELISA assay developed in our laboratory (Mabjeesh et al 2007;Mabjeesh et al 2013). Briefly, ELISA plates (Nunc, Thermo, Denmark) were coated with 1 µg/ml of monoclonal mouse anti-prolactin IgG1 (clone 6F11, Abnova, Taiwan) diluted in carbonate-bicarbonate buffer, pH 9.6 (Thermo, IL, USA) and incubated in a humidified chamber at 4°C overnight.…”

Exposure to ergot alkaloids during gestation reduces fetal growth in sheep

“…The reduction in serum PRL concentration with exposure to ergot alkaloids via grazing endophyte-infected tall fescue pastures or consumption of endophyte-infected tall fescue seed is a classical response observed in sheep (Elsasser and Bolt, 1987; Emile et al, 2000; Parish et al, 2003), cattle (Emile et al, 2000; Watson et al, 2004; Koontz et al, 2012; Stowe et al, 2013), and horses (McCann et al, 1992). It has been documented in multiple species that as parturition approaches maternal serum PRL concentration increases (Chamley et al, 1973; Bryant and Chamley, 1976; Forsyth, 1986) and this increase is hypothesized to be important for maternal lipid metabolism, mammary growth, and milk production and secretion (Hooley et al, 1978; Banchero et al, 2006; Mabjeesh et al, 2013). The levels of PRL reported here for the E− group are consistent with previous reports; however, the drastically lower levels observed at d 130 for E+ could indicate post-partum issues with ewe metabolism and mammary growth, which would negatively impact postnatal lamb growth.…”

Respons Fisiologis Dan Ketahanan Panas Kambing Boerawa Dan Peranakan Ettawa Pada Modifikasi Iklim Mikro Kandang Melalui Pengkabutan

“…Konsekuensi dari cekaman panas atau toleransi panas yang rendah secara langsung adalah terjadinya penurunan produktivitas ternak, baik pertumbuhan, produksi susu, maupun reproduksi. Mabjeesh et al (2013) melaporkan bahwa terjadi penurunan produksi susu pada kambing yang terkena cekaman panas. Parameter lain yang menunjukkan cekaman panas adalah adanya perubahan fisiologis dan tingkahlaku, yaitu penurunan nafsu makan dan metabolisme, peningkatan konsumsi air minum, peningkatan pengeluaran panas melalui evaporasi; penurunan konsentrasi hormon metabolis dalam darah, peningkatan suhu tubuh, frekuensi pernafasan, dan denyut jantung (Qisthon dan Suharyati, 2007;Aguilar et al, 2010;dan Seixas et al, 2017).…”