Caja, G. | Search bioRxiv

bioRxiv2019

Prenatal heat stress effects on gestation and postnatal behavior in kid goats

Consequences of heat stress during pregnancy can affect the normal development of the offspring. In the present experiment, 30 Murciano-Granadina dairy goats (41.8 {+/-} 5.7 kg) were exposed to 2 thermal environments varying in temperature-humidity index (THI) from 12 days before mating to 45 days of gestation. The environmental conditions were: gestation thermal-neutral (GTN; THI = 71 {+/-} 3); and gestation heat stress (GHS; THI = 85 {+/-} 3). At 27 {+/-} 4 days old, GTN-born female kids (n = 16) and GHS-born ones (n = 10) were subjected to 2 tests: arena test (AT) and novel object test (NOT), the latter was repeated at 3 months of age. Additionally, 8 months after birth, a subset of growing goats (n = 8) coming from GTN and GHS (16.8 {+/-} 3.4 kg BW) were exposed consecutively to 2 environmental conditions: a basal thermal-neutral period (THI = 72 {+/-} 3) for 7 days, and a heat-stress period (THI = 87 {+/-} 2) for 21 days. In both periods, feeding behavior, resting behavior, other active behaviors (exploring, grooming), thermally-associated behaviors and posture were recorded. The gestation length was shortened by 3 days in GHS goats. In the AT, GHS kids showed a lower number of sniffs (P < 0.01) compared to GTN. In the NOT, GHS kids also tended to show a lower number of sniffs (P = 0.09). During heat exposure, GTN and GHS growing goats spent more time resting as well as exhibited more heat-stress related behaviors such as panting and drinking (P < 0.001); however, no differences were observed between both groups. In conclusion, heat stress during the first third of pregnancy shortened gestation length and influenced the exploratory behavior of the kids in the early life without impact on the behavior during the adulthood when exposed to heat stress.

animal behavior and cognition↗

bioRxiv2018

Heat stress modifies the lactational performances and the urinary metabolomic profile related to gastrointestinal microbiota of dairy goats

The aim of the study was to identify the candidate biomarkers of heat stress (HS) in the urine of lactating dairy goats through the application of proton Nuclear Magnetic Resonance (1H NMR)-based metabolomic analysis. Dairy does (n = 16) in mid-lactation were submitted to thermal neutral (TN; indoors; 15 to 20{degrees}C; 40 to 45% humidity) or HS (climatic chamber; 37{degrees}C day, 30{degrees}C night; 40% humidity) conditions according to a crossover design (2 periods of 21 days). Thermophysiological traits and lactational performances were recorded and milk composition analyzed during each period. Urine samples were collected at day 15 of each period for 1H NMR spectroscopy analysis. Principal component analysis (PCA) and partial least square-discriminant analysis (PLS-DA) assessment with cross validation were used to identify the goat urinary metabolome from Human Metabolome Data Base. HS increased rectal temperature (1.2{degrees}C), respiratory rate (3.5-fold) and water intake (74%), but decreased feed intake (35%) and body weight (5%) of the lactating does. No differences were detected in milk yield, but HS decreased the milk contents of fat (9%), protein (16%) and lactose (5%). Metabolomics allowed separating TN and HS urinary clusters by PLS-DA. Most discriminating metabolites were hippurate and other phenylalanine (Phe) derivative compounds, which increased in HS vs. TN does. The greater excretion of these gut-derived toxic compounds indicated that HS induced a harmful gastrointestinal microbiota overgrowth, which should have sequestrated aromatic amino acids for their metabolism and decreased the synthesis of neurotransmitters and thyroid hormones, with negative impact on milk yield and composition. In conclusion, HS markedly changed the thermophysiological traits and lactational performances of dairy goats, which were translated into their urinary metabolomic profile through the presence of gut-derived toxic compounds. Hippurate and other Phe-derivative compounds are suggested as urinary biomarkers to detect heat stressed dairy animals in practice.

systems biology↗