Seasonal variation in body mass index, cardinal physiological variables and serum thyroid hormones profiles in relation to susceptibility to thermal stress in goat kids

Thermoregulation in periparturient rabbit does and their neonatal kits with different litter sizes during West African winter

The study evaluated the changes in body temperatures and hematological parameters in periparturient rabbit does and the dynamics of body surface temperature in neonatal rabbit kits during West African winter. The variables were measured in 21 rabbits, comprising periparturient (n = 12) and dry (n = 9) does, and after kindling, the kits were grouped based on litter size, into small (4 kits per litter; n = 24) and large (5-7 kits per litter; n = 34) litter. Results revealed that all body temperatures of the does were lower (p < 0.05) during gestation compared with lactation period or dry does in all hours of the day, and the PCV was significantly higher in lactating than dry does. At birth, small litter kits had higher (p < 0.05) body weight and morning body surface temperature than the large litter kits. The large litter kits showed distinct (p < 0.05) diurnal variation in body surface temperature from birth, while diurnal variation in the small litter kits was absent (P > 0.05) in the first three days after birth. It was concluded that pregnant rabbits and large litter kits may have poor thermoregulation during West African winter, and thus, the need for special protective housing to improve productivity.

Role of maternal variables on the development of neonatal hypoglycaemia and influence of neonatal hypoglycaemia on performance of goat kids

The study evaluated the influence of maternal variables (age, body weight and body mass index; BMI) during mating on the development of hypoglycaemia and investigated whether hypoglycaemia at birth impairs thermoregulation, metabolism, body weight gain and immunoglobulin concentration in neonatal goat kids. Post-kidding, the kids born with hypoglycaemia (n = 19) and normoglycaemia (n = 19) were immediately identified and postnatal blood samples, body weight and cardinal physiological variables were determined. Results revealed no significant (P < 0.05) difference in pre-mating maternal variables between dams that kidded hypoglycaemic and normoglycaemic kids. Kids born with hypoglycaemia had lower (P <0.05) blood glucose concentration from birth, until Day 2, when values became comparable between the two groups. Afternoon respiratory and pulse rates were markedly (P < 0.05) unstable in kids born with hypoglycaemia and the early postnatal rise (P < 0.05) in morning rectal temperature in both groups was accompanied by a decrease (P < 0.05) on day 20 in kids born with hypoglycaemia. Blood cholesterol and triglyceride concentrations were lower (P < 0.05) in hypoglycaemic kids and the normoglycaemic kids showed marked increase (P < 0.05) in circulating immunoglobulin concentration 24 h after birth, while age had no (P > 0.05) effect in hypoglycaemic kids. A more pronounced decrease (P < 0.05) in weekly weight gain was observed in hypoglycaemic kids. It was concluded that neonatal goat kids born with hypoglycaemia may have compromised thermoregulation, metabolism and body weight gain, and the cause of hypoglycaemia in kids may not be related to pre-mating maternal variables.

Cold and heat climatic variations reduce indigenous goat birth weight and enhance pre-weaning mortality in subtropical monsoon region of China

The subtropical monsoon climate characterized by high or low temperature and humidity can induce cold and heat stress for newborn animals, which results in adverse effect on birth weight and even pre-weaning mortality. However, this early growth performance on indigenous goats is affected by cold and heat climatic environments and is still unclear in subtropical climate. In this study, we continuously measured (July 2011 to June 2016) the birth weight and mortality of an indigenous goat species (n = 530), and collected temperature, humidity, temperature-humidity index (THI) in original farming area, Chongqing, southwest China. As the result, the mean birth weights in cold months (January and February, mean temperature < 10 °C and THI < 56) and heat months (July and August, mean temperature > 29 °C and THI > 76) were significantly lower (P < 0.05) compared to the other months (June and October, mean temperature = 16~25 °C and THI = 61~75). Meanwhile, the birth weight was positively correlated (P < 0.01) with gestational THI from November to May, and was negatively correlated (P < 0.01) with those parameters from June to October, respectively. The maximum pre-weaning mortality, occurring in the 1st month after birth, is 16.17 ± 2.56%. However, when the birth weight was 20% lower than annual average (2.09 ± 0.54 kg), the mortality was significantly enhanced (P < 0.01) to 46%. In addition, cold and heat climates respectively enhanced mortality in the 1st month and 2nd~4th months after birth. In conclusion, annually chronic heat and cold climates could play important roles in lowering birth weight and their survival in subtropical monsoon region. Low birth weight and cold temperature play critical role to contribute the advent of higher mortality after birth. Our results potentially provide the appropriate ranges of temperature (16~26 °C) and THI (61~75) as pregnant goat and kids raising condition to avoid these negative influences.

Sensitivity, Impact and Consequences of Changes in Respiratory Rate During Thermoregulation in Livestock – A Review

This review discusses the thermal conservative and heat dissipating roles of one of the most sensitive thermoregulatory variables (respiratory rate) with the aim of enhancing its application in evaluating both cold and heat adaptation. During cold exposure, livestock enhance the economy of body heat through reduction in respiratory rate with the extent of reduction being greater and commencing at relatively higher ambient temperature in poorly adapted phenotypes. This is accompanied by an increase in tidal volume and alveolar oxygen uptake, but a decrease in partial pressure of oxygen. On the other hand, heat stress induces increase in respiratory rate to enhance evaporative heat loss with the magnitude of such increase being greater and commencing at relatively lower ambient temperature in phenotypes that are poorly-adapted to heat. This is accompanied by a decrease in tidal volume and the development of hypocapnia. The increase in respiratory rate is observed to be greater, moderate and lesser in livestock that are mainly (pigs, rabbits and poultry), moderately (sheep, goats and Bos taurus) and less (Zebu cattle) dependent on respiratory evaporative heat loss, respectively. The changes during chronic heat stress may cause acid-base crisis in all livestock, in addition to reduction in eggshell quality in birds; due to marked decrease in partial pressure of carbon dioxide and a compensatory increase in elimination of bicarbonate. Within and between breed variations in sensitivity of respiratory rhythm to both cold and heat stress has shown high applicability in identifying phenotypes that are more susceptible to thermal stress; with some cellular and metabolic changes occurring to protect the animal from the consequences of hypo- or hyper-thermia. The information in this review may provide basis for identification of genes that support or suppress thermoregulation and may also be of great use in animal breeding, genomics and selective thermal stress mitigation to provide maximum protection and comfort to poorly-adapted phenotypes.

Resilience of three indigenous goat breeds to heat stress based on phenotypic traits and PBMC HSP70 expression

The objective of this experiment was to evaluate the influence of summer heat stress on physiological and behavioral responses of Osmanabadi, Salem Black, and Malabari goats. The study also evaluated the differences in heat shock protein 70 (HSP70) expression pattern between these breeds. The study was conducted over 45 days during summer (April-May) using 36 1-year-old female goats by randomly allocating them into six groups with six animals in each group: Osmanabadi control (Osmanabadi CON), Osmanabadi heat stress (Osmanabadi HS), Malabari control (Malabari CON), Malabari heat stress (Malabari HS), Salem Black control (Salem Black CON), and Salem Black heat stress (Salem Black HS). The Osmanabadi CON, Malabari CON, and Salem Black CON animals were housed in a shed while the Osmanabadi HS, Malabari HS, and Salem Black HS groups were subjected to heat stress by exposing them to outside environment between 1000 and 1600 h during the experimental period. All 36 animals were provided with ad libitum feed and water. The data generated were analyzed by general linear model (GLM) repeated measurement analysis of variance. Results indicated that the drinking frequency (DF) was higher (p < 0.01) in heat stress groups (12.58, 12.25, and 10.75 times for the Osmanabadi HS, Malabari HS, and Salem Black HS, respectively) as compared to their respective control groups (5.67, 6.25, 5.58 times for the Osmanabadi CON, Malabari CON, and Salem Black CON, respectively). Water intake (WI) also showed similar trend to DF. The urinating frequency also (UF) differed between breeds with lower value (p < 0.05) recorded in the Salem Black HS (1.5 times) compared to the Malabari HS (2.92 times). The highest (p < 0.05) rumination time (RuT) was recorded in the Malabari HS (48.00 min) than both the Osmanabadi HS (20.91 min) and Salem Black HS (23.67 min). The heat stress increased (p < 0.05) all physiological variables at 1400 h. The findings of this study suggest RR, RT, and PBMC HSP70 are reliable biological markers for evaluating thermo-tolerance capacity of indigenous goat breeds.

Comparative assessment of growth performance of three different indigenous goat breeds exposed to summer heat stress

A study was conducted to assess comparatively the growth performance of three different indigenous goat breeds during exposure to summer heat stress. The primary objective of the study was to observe the heat stress impact on the growth performance based on the body weight changes, allometric measurements, growth hormone (GH) concentration and peripheral blood mononuclear cell (PBMC) Insulin-like growth factor-1 (IGF-1) mRNA expression pattern during the summer season in comparison with the local breed (Osmanabadi). Thirty-six ten-month- to one-year-old female goats of Osmanabadi, Malabari and Salem Black breeds were randomly divided into six groups, OC (n = 6; Osmanabadi control), OHS (n = 6; Osmanabadi heat stress), MC (n = 6; Malabari control), MHS (n = 6; Malabari heat stress), SBC (n = 6; Salem Black control) and SBHS (n = 6; Salem Black heat stress). Body weight was recorded at weekly intervals, whereas other growth and allometric measurements and blood collection were carried out at fortnightly intervals. Breed factor significantly (p < .05) influenced only few growth variables such as body weight, body mass index (BMI) and body condition score (BCS). However, heat stress treatment significantly (p < .05) reduced all growth parameters expect BMI. Further, the heat stress significantly (p < .01) increased plasma GH concentration in goats with significantly higher (p < .05) concentration recorded in OHS. Among the stress groups, the lower (p < .05) PBMC IGF-1 mRNA expression was recorded in OHS, while the higher (p < .05) expression was observed in SBHS indicating the extreme adaptive capability of Salem Black breed. Thus, the results indicated that the Salem Black breed performed much better compared to both Osmanabadi and Malabari breeds indicating the superior ability of this breed to adapt to heat stress challenges. The results also indicated that plasma GH and IGF-1 gene may act as ideal biomarkers for assessing the heat stress impact on growth performance in indigenous goats.

Hair coat characteristics and thermophysiological stress response of Nguni and Boran cows raised under hot environmental conditions

Breed, age, coat colour, month and temperature humidity index (THI) influence on body weight (W), body condition score (BCS), thermophysiological variables (rectal temperature (Tr), skin temperature (Tsk)) and hair length was studied in Nguni (n = 19) and Boran (n = 16). As a result of this study, breed influenced W, BCS and Tsk on the neck and belly (P < 0.05). The BCS and W of Nguni cows were higher than the Boran cows. Hair length of both breeds increased from February to August. The THI influenced thermophysiological variables (P < 0.05). Increased Tr for both breeds was recorded in February and April, respectively (P < 0.05). Month influenced Tsk and June recorded lower values (P < 0.05). Younger cows (3-8 years) had lower weight and high Tr and Tsk (P < 0.05). Nguni cows had high neck and thurl temperatures in June while Boran cows had the highest in August (P < 0.05). Red, dun and white-black Boran cows had increased BCS. Nguni cows with red, fawn and white cows had high BCS. Fawn-coloured Nguni cows and white-brown Boran cows had the more weight than cows with other colours compared in the study. White-red Nguni and Boran cows recorded the highest Tr. For Nguni cows, neck and belly temperatures were significantly (P < 0.001) correlated to thurl temperature. Boran cows had significant (P < 0.001) correlations for THI and neck, belly and thurl temperatures. The current study found that Nguni cows were more adapted to the prevailing bioclimatic changes. However, Boran cows have the potential of performing well under heat stress conditions over time.

Diurnal thermoregulatory responses in pregnant Yankasa ewes to the dry season in a tropical Savannah

The study investigated concomitant effect of gestation and high ambient temperature under a tropical environment on rectal temperature (RT), respiratory rate (RR) and heart rate (HR) responses in Yankasa ewes. Twenty Yankasa ewes, consisting of ten pregnant and ten non-pregnant ewes, were used for the study. Ewes were synchronised and bred, such that each gestation phase coincided with different periods of the dry-seasons, early-gestation (cold/harmattan), mid-gestation (peak hot-dry) and late-gestation (late hot-dry). The RT, RR and HR were recorded thrice, 2 days apart at middle of each gestation period at 06:00, 14:00 and 18:00 h, concurrently with dry- (DBT) and wet-bulb temperatures of the experimental pen. The DBT was positively correlated with RT, RR during the different gestation stages. The RT significantly (P < 0.001) increased with the hour of day, regardless of the physiological status of the ewes, with peak at 14:00 h. Values of RT and RR were higher (P < 0.05) in pregnant than non-pregnant ewes at mid- and late-gestation, respectively. Mean RT was lower (P < 0.001) at 06:00 h in pregnant than non-pregnant ewes at early-gestation (cold-dry). The HR was (P < 0.05) higher in pregnant than non-pregnant ewes during the different gestation phases. In conclusion, ambient temperature and gestation concomitantly modulate diurnal thermoregulatory responses of the ewes to hot-dry season. Adequate measures should be adopted to mitigate adverse impact of prolonged high RR on the dam and the foetus during the peak of ambient temperature prevailing in the tropical Savannah environment.

Influences of breed, sex and age on seasonal changes in haematological variables of tropical goat kids

Abstract. The influences of breed, sex and age on seasonal changes in haematological variables of kids (1–4 months old) belonging to Red Sokoto (n  =  60) and Sahel (n  =  60) goats were studied at the peaks of the cold-dry, hot-dry and rainy seasons in a West Africa Guinea savanna climate. The results showed that, during the hot-dry season, Sahel goat kids had significantly higher (P  <  0.05) packed cell volume (PCV) and red blood cell (RBC) count but lower (P  <  0.05) mean corpuscular volume (MCV), mean corpuscular haemoglobin (MCH), mean corpuscular haemoglobin concentration (MCHC) and total leucocyte count than Red Sokoto kids. Similarly, younger kids of both breed had significantly higher (P  <  0.05) PCV and RBC but lower MCV, MCH and MCHC compared with the older kids during the hot-dry season. Younger kids (1–2 months) of both breeds exhibited significantly (P  <  0.05) high PCV and RBC but low MCH and MCHC during the hot-dry season as compared with the cold-dry and rainy seasons, with the magnitude of the change being greater in Sahel kids. More remarkable seasonal fluctuations in haematological parameters were observed in buck kids than doe kids of both breeds. Multivariate analysis revealed a clear distinction between the change in haematological parameters during the cold-dry as compared with the hot-dry and rainy seasons, with MCV having the strongest discriminating power (0.91*). In conclusion, breed, age and sex variations in haematological variables of goats were more pronounced in the hot-dry season, during which the seasonal changes were more dramatic in kids of Sahel goats, as well as in younger and male kids of both breeds. These findings may be useful in the management of tropical goat kids in different seasons.