Late-gestation heat stress impairs daughter and granddaughter lifetime performance

Abstract

Records of late-gestation heat stress studies conducted over 10 consecutive years in Florida were pooled and analyzed to test the hypothesis that maternal hyperthermia during late gestation impairs performance of the offspring across multiple generations and lactations, ultimately impeding the profitability of the US dairy sector. Dry-pregnant multiparous dams were actively cooled (CL; shade of a freestall barn, fans and water soakers, n = 196) or not (HT; shade only, n = 198) during the last 46 d of gestation, concurrent with the entire dry period. After data mining, records of 156 daughters (F 1 ) that were born either to CL (CL F1 , n = 77) or HT dams (HT F1 , n = 79) and 45 granddaughters (F 2 ) that were born either to CL F1 (CL F2 , n = 24) or HT F1 (HT F2 , n = 21) were used in the analysis. Life events and daily milk yield for 3 lactations of daughters and granddaughters were obtained. Milk yield, reproductive performance, and productive life data were analyzed using MIXED and GLIMMIX procedures, and lifespan was analyzed using PHREG and LIFETEST procedures of SAS (SAS Institute Inc., Cary, NC). Milk production of HT F1 was reduced in their first (2.2 kg/d), second (2.3 kg/d), and third lactations (6.5 kg/d) compared with CL F1 . More HT F1 were culled before first calving, and the productive life and lifespan of HT F1 were reduced relative to CL F1 (4.9 and 11.7 mo, respectively). The granddaughters (HT F2 ) born to HT F1 produced less milk in their first lactation (1.3 kg/d) relative to granddaughters (CL F2 ) born to CL F1 . More HT F2 were culled before first breeding relative to CL F2 ; however, productive life and lifespan were not different between HT F2 and CL F2 animals. An economic analysis was then performed based on the number of heat stress days, dry cows per state, and the aforementioned impairments on daughters' lifespans and milk production. Collectively in the United States, the economic losses for additional heifer rearing cost, reduced productive life, and reduced milk yield of the F 1 offspring were estimated at $134, $90, and $371 million per year, respectively. In summary, late-gestation heat stress exerts carryover effects on at least 2 generations. Providing heat abatement to dry-pregnant dams is important to rescue milk loss of the dam and to prevent losses in their progeny.

Critical Temperature-Humidity Index Thresholds for Dry Cows in a Subtropical Climate

“…Animalbased indicators recognize heat stress more accurately than environmental ones, as they account for differences between individuals and differences in management systems (Galán et al, 2018). However, environmental indicators, particularly THI, remains widely used, especially in heat-stress economic studies (St-Pierre et al, 2003;Key and Sneeringer, 2014;Ferreira et al, 2016;Laporta et al, 2020), and for on-farm heat stress abatement strategies (Fournel et al, 2017). In addition, environmental indicators are practical as they allow for assessment of heat stress in retrospective studies including large numbers of animals (Bernabucci et al, 2014;Ouellet et al, 2019a).…”

Across-generation effects of maternal heat stress during late gestation on production, female fertility and longevity traits in dairy cows

“…Laporta et al . (2020) identified persisting HS impairments through multiple generations: granddaughters from heat stressed grandmothers produced less milk and had a higher culling than cows from the control group.…”

Problems of livestock reproduction with a focus on climate change

“…There was a decrease in daughters and granddaughters' daily milk yield and a reduction in their productive life in the herd. The United States' losses run into hundreds of millions of dollars per year (Laporta et al 2020). However, this is not a critical issue for the middle-yielding cows in a moderately continental climate of Europe (Borş et al 2019).…”

“…Decreasing yields and plant nutrient value as a natural fodder base for livestock, favourable environment for the pathogenic bacteria developing and spreading, as well as the direct effect of high temperatures on animal welfare are the causes of significant losses in livestock worldwide associated with climate change (Laporta et al 2020). On the other hand, long-term selection for high milk yield has led to limited oestrus in modern dairy cattle compared to the animals studied by researchers 40 years ago (Sheldon et al 2011).…”