During my recent invited talk on climate change and its concomitant impacts, I been asked on similar query (impact of climate change on herd): I remember. My answer was
Increase in temperature purportedly linked to rise in metabolic diseases and therefore it may leads to decrease in the reproduction and reduced eggs, and other associated problems in herd.
Hope the reference below you may find useful.
M. Melissa Rojas-Downing, A. Pouyan Nejadhashemi, Timothy Harrigan & Sean A.Woznicki, (2017). Climate change and livestock: Impacts, adaptation, and mitigation, Climate risk Management, 16, 145-163.