Are crossbred cattle (F1, Bos indicus x Bos taurus) thermally different to the purebred Bos indicus cattle under moderate conditions?

Author(s)

Moura, Gustavo Andre Bernado ^[1] ; Costa, Cintia Carol de Melo ^[1] ; Fonseca, Vinicius de Franca Carvalho ^{[1, 2]} ; Wijffels, Gene ^[3] ; Castro, Patric Andre ^[1] ; Neto, Marcos Chiquitelli ^[4] ; Maia, Alex Sandro Campos ^[1]

Affiliation

^[1] Sao Paulo State Univ, Sch Agr & Veterinarian Sci, Innovat Grp Biometeorol & Anim Welf INOBIO MANERA, BR-14884900 Jaboticabal - Brazil

^[2] Univ Witwatersrand, Sch Physiol, Brain Funct Res Grp, ZA-2193 Johannesburg - South Africa

^[3] CSIRO Agr & Food, St Lucia, Qld 4067 - Australia

^[4] Sao Paulo State Univ, Sch Nat Sci & Engn, Innovat Grp Biometeorol & Anim Welf INOBIO MANERA, BR-15385000 Ilha Solteira - Brazil

• Document type: Journal article
• Source: LIVESTOCK SCIENCE; v. 246, APR 2021.
• Web of Science Citations: 0

Abstract

In this study we compared the bio-thermal responses of a crossbred (F1, Nellore x Angus) and purebred Bos indicus (Nellore) cattle kept under moderate thermal conditions. Specifically, we assessed if they were different in their daily pattern of metabolic heat production, regulation of body temperature and use of evaporative heat transfer pathways. Six Nellore bulls with 669 +/- 65 kg of body weight and twelve crossbred bulls (F1, Nellore x Angus) with 606.5 +/- 25.09 kg of body weight, were evaluated in two experiments. Individual bulls were secured and attached to instruments in the biometeorology laboratory to enable recording of the proportion of respiratory gases in the exhaled air (oxygen, O-2; carbon dioxide, CO2), saturation pressure of the exhaled air (PS[T-EXP], kPa) and skin surface (PS[T-SKIN], kPa), respiratory rate (R-R, breath min(-1)), ventilation rate (VE, L s(-1)); skin (T-SKIN, degrees C), hair coat (T-S, degrees C), rectal (T-R, degrees C) and exhaled air temperatures (T-EXP, degrees C) from 0600 to 1800 h. The air temperature over the two experiments ranged from 16 to 30 degrees C. The mean of metabolic heat production was higher for crossbred (2.24 W kg(-1)) than Nellore cattle (1.09 W kg 1) (P <0.0001), as the crossbred had higher values for ventilation rate (P <0.0001), and proportion of the oxygen extracted from the inhaled air. Slight differences for thermal storage and daily fluctuation of daytime rectal temperature (0730 and 1630 h) were also observed, ranging from 39 to 39.30 degrees C for Nellore cattle and from 39.12 to 39.62 degrees C for the crossbred. Both genotypes increased heat loss through cutaneous evaporation with rising air temperature, which was slightly higher for the crossbred cattle. In conclusion, under the moderate thermal conditions of the present study, the crossbred cattle had higher levels of heat production, thermal storage and cutaneous evaporation than the purebred Nellore cattle. Further, it appears that both genotypes were able to maintain their thermal balance with relatively low energy demand for thermoregulation. (AU)

• FAPESP's process: 14/11170-7 - Study of thermal equilibrium associate with CH4 emission in Nelore cattle managed in the field during a period of 24 hours
• Grantee: Cíntia Carol de Melo Costa
• Support Opportunities: Scholarships in Brazil - Doctorate
• FAPESP's process: 11/17388-6 - Effects of solar radiation and air temperature on methane emission as associated with metabolic heat production and latent heat loss in ruminants
• Grantee: Alex Sandro Campos Maia
• Support Opportunities: Regular Research Grants
• FAPESP's process: 16/12278-1 - Evaluation of different methods for the measurement of heat loss by cutaneous evaporation in animals
• Grantee: Vinícius de França Carvalho Fonsêca
• Support Opportunities: Scholarships in Brazil - Post-Doctoral
• FAPESP's process: 18/19148-1 - Shading with photovoltaic panels to beef cattle: a study on thermal equilibrium, on the economic viability and environmental impact
• Grantee: Alex Sandro Campos Maia
• Support Opportunities: Research Program on Global Climate Change - Regular Grants