Influence of the Climatic Environment on the Mother-Offspring Interaction in Morada Nova Sheep

Influence of the climatic environment on the mother-offspring interaction in Morada Nova sheep

Vinícius F.C. Fonsêca1, Edílson P. Saraiva1, Edgard C. Pimenta Filho1, Dermerval A. Furtado2, Mikael L.C. Amorim1, Maria E. V. Ameida1 Tarsys N.S. Veríssimo1

1 Federal University of Paraíba – UFPB 2 Federal University of Campina Grande – UFCG

Even in Brazil, a country with a tropical climate, a newborn can suffer stress from cold, especially during labors that occur at night. Newborn lambs are highly susceptible to hypothermia due to their high surface area to mass ratio and because they have trouble conserving heat, as they are wet when born and do not have a well-developed insulating surface. A good portion of the energetic supply for the newborn comes from colostrum, and the faster they access the udder, the greater their chances of surviving the adversities of the external environment. Thus, the objective of this study was to evaluate the influence of the BGTHI (Black globe temperature and humidity index) at the time of the birth on the formation of the mother-offspring bond in Morada Nova sheep. The study was conducted in the Small Ruminants Research Unit of the Experimental Station of São João do Cariri (07°23'27'' S, 36°31'58'' W, 458m altitude), which belongs to the Agrarian Sciences Center of the Federal University of Paraíba – UFPB. Data were collected on 80 Morada Nova multiparous ewes and their 80 lambs. Based on the average of BGTHI (black globe temperature-humidity index) at the time of the birth, the ewes were grouped into three ranges: low (less than 65), intermediate (greater than 65 and less than 80) or high (greater than 80). Ten days prior to the predicted labor date, the ewes were taken to a maternity pen (6-m wide and 12-m long) with a conventional floor of washed sand. A set of thermometers was placed in the interior of the pen at a height of 1.0 m from the floor for the collection of the environmental data, including ambient temperature (AT), black globe temperature (BGT), air relative humidity (RH) and wind speed (Ws). The climatic variables were measured every two hours, 24 hours per day. With the climatic data, the black globe temperature-humidity index (BGTHI) was calculated according to the equation: BGTHI = BGT + 0.36 DPT – 330.08, where, BGT is black globe temperature (K); and DPT is dew-point temperature (K). To characterize the mother-offspring behavior, evaluations were performed from the first apparent signs of labor until the first two hours after birth or at the moment of the first suckling of the newborn. When the neonate was unable to suckle within two hours, a latency to suckle value of 120 minutes was assumed. In the case of twin births, the observation as conducted only for the first lamb. The observations were carried out in a direct and continuous manner by the method of focal animal sampling from a previously prepared ethogram for the records of duration (time) and frequency (n) of the behavioral states and events of the ewes and the newborns. The ewes were marked with non-toxic black paint on the right and left sides to facilitate their identification by the observers at the time of evaluation. During the postpartum observations, maternal factors such as maternal grooming (percentage of total observation time spent cleaning the newborn), facilitating sucking (percentage of total observation time in which the ewe exposes her udder to the newborn or remains still while the lamb seeks the udder), frequency of low-pitched bleats (expressed as the number of occurrences per minute that the ewe vocalizes with her mouth closed) and the time until the ewe touched the lamb (latency to groom) were recorded. For the lambs, attempts to seek the udder (percentage of total observation time that the lamb spent in the parallel inverse position with its head nudging the ewe in the udder region), the frequency of low-pitched bleats (expressed as the number of occurrences per minute that the newborn vocalized with its mouth closed), the time until the lamb raised and shook its head (latency to first reaction), the time taken by the lamb to place its four legs on the ground for a period of approximately five seconds (latency to stand) and the time until the newborn performed its first successful suckling (latency to suckle) were recorded. A generalized linear model (GLIMMIX procedure) was used to examine the effect of ranges of BGTHI (low, intermediate or high), on the maternal and neonatal behaviors. The lambs were slower (P < 0.05) to stand when they were born under BGTHI conditions below 65. Additionally, the time elapsed for the execution of the first suckling (latency to suckle) was lower (P < 0.05) when the index was equal to or greater than 80 . However, the latency to the first reaction of the newborns did not differ (P > 0.05) as a function of the BGTHI range. Under BGTHI conditions in which the newborns were slower to suckle, the lambs spent more time seeking the udders of their mothers (P < 0.05). There were differences (P > 0.05) in the frequency of low-pitched bleats between lambs experiencing different BGTHI conditions at birth. This frequency was greater (P < 0.05) when the lambs were born under BGTHI conditions below 65. Among the maternal behavioral progress, the time elapsed until the dams touched their lambs (latency to groom) was not affected (P > 0.05) by the range of the bioclimatic index. However, maternal grooming and the facilitation of suckling occurred more often (P < 0.05) during the time periods with higher bioclimatic index values (> 80). Moreover, the low-pitched bleats were emitted at similar (P > 0.05) frequencies in the different BGTHI ranges. From the present study, it can be concluded that, Newborn Morada Nova lambs are slower to stand and suck when born under BGTHI conditions below 65. Therefore, lambs born in periods with lower temperatures require greater care from the breeder, especially during the first 24 hours after birth.