Effect of heat stress on conception in a dairy herd model under South African conditions

Preez, J.H. Du; Terblanche, Susan; Giesecke, W.H.; Maree, C; Welding, M.C.

doi:10.1016/0093-691x(91)90313-3

Cited by 15 publications

(10 citation statements)

References 9 publications

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“…While the treatment of animal exposed to heat stress with antioxidant will elevate the pregnancy rate in the heat‐stressed animals. This is in accordance with the results of Du Preez et al. (1999), who found that heat stress decreases the conception rate in dairy cows.…”

Section: Discussionsupporting

confidence: 93%

Influence of Heat Stress on the Cortisol and Oxidant‐Antioxidants Balance During Oestrous Phase in Buffalo‐Cows (Bubalus bubalis): Thermo‐protective Role of Antioxidant Treatment

Megahed¹,

Mohammad

Wasfy

et al. 2008

Reprod Domestic Animals

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In the present study, the effect of heat stress, which is commonly observed in the animals of Upper Egypt area in summer, as well as the effect of antioxidant treatment as a thermo-protective was examined. In this study, the animals (n = 120) were divided into winter group (n = 40, bred during winter) and summer group (n = 80, bred during summer) as well as, animals in the summer group were divided into first subgroup animals (n = 40) and injected with Viteselen intramuscularly (15 ml) twice weekly for 10 weeks and second subgroup animals (n = 40) were not treated (as control). Serum levels of progesterone (P4), oestradiol (E2), cortisol, superoxide dismutase (SOD), lipid peroxidase (LPO) and nitric oxide (NO) were measured. The pregnancy rate of all animals was detected rectally. The levels of oestradiol and the activity of the antioxidant SOD were decreased in serum of animals in behavioural oestrus during summer as compared with those in winter. During the same time period the levels of oxidants such as LPO and NO were increased in the serum of animals again in the phase of oestrus. In another group of animals treated by intramuscular injection with 15 ml viteselen (antioxidant) twice weekly for 6 weeks during hot months, the activities of serum SOD showed an increase and the levels of oxidants and cortisol decreased. Moreover, the levels of oestradiol were increased during the oestrous behaviour. The pregnancy rate was decreased in animals under heat stress and the pregnancy rate was enhanced dramatically when these animals received antioxidants during the heat stress. This means that the heat-stress in Upper Egypt may affect the fertility of animals and pregnancy rate and this effect may be through an increased production of free radicals and decreased production of antioxidants as well as increased levels of cortisol. Treatment of animals or supplementation with antioxidants before the beginning of months of heat-stress and also during the stress period may correct the infertility due to heat-stress through the decrease in cortisol secretion and a decrease in the oxidative stress. These results resulted in an increase in pregnancy rate in treated animals.

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Section: Discussionsupporting

confidence: 93%

Influence of Heat Stress on the Cortisol and Oxidant‐Antioxidants Balance During Oestrous Phase in Buffalo‐Cows (Bubalus bubalis): Thermo‐protective Role of Antioxidant Treatment

Megahed¹,

Mohammad

Wasfy

et al. 2008

Reprod Domestic Animals

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“…These results are in agreement with findings reported by Ingraham et al (1976) andDu Preez et al (1991). Our previous work (Ben Salem et al, 2006) showed that feeding and management strategies of most dairy herds in Tunisia are inadequate and barns are lacking heat stress control techniques which aggravate the observed negative effects of heat stress on cow performances.…”

Section: Resultssupporting

confidence: 83%

Heat Stress in Tunisia: Effects on dairy cows and potential means

Salem¹,

Bouraoui²

2010

SA J. An. Sci.

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Tunisia has a Mediterranean climate characterized by high ambient temperatures for a long period. Thus, one of the challenges to dairy producers is heat stress. The objectives of this work were to characterize the environmental conditions to which Holstein cows are exposed in Tunisia using the Temperature Humidity Index (THI), examine heat stress effects on lactating cows and to suggest potential management strategies that can be used to reduce such effects. THI values were calculated using a 10-year period average monthly temperature and relative humidity data from different weather stations. Milk production and its relationship with THI were than examined using the data of herds under the dairy herd recording programme. Reproductive indices were calculated using data from four selected herds and their relationships with corresponding THI values were examined. Results showed that summer heat stress prevails in Tunisia for four to five months going from May to September with THI values being greater than 72. The highest THI values were recorded for summer and early fall. Milk yield per cow dropped by about 10% between March and August. First conception (CRI1) and overall conception rates (CR) were lowest in the summer and highest in winter. Regression equations between THI and CRI1 and THI and CR had high R 2 values suggesting a strong relationship between heat stress and reproduction. Maintaining cow performance under hot conditions requires the adoption of environmental control techniques, appropriate feeding strategies, improved nutritional practices, and genetic improvement programs such as crossbreeding for enhanced heat tolerance.

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“…This study identified a THI of 70 as a threshold, since the average milk production in South Africa is about 22.5 L per cow ( Milk SA, 2015 ), which is a fair threshold chosen for such a quantity of production ( Berman, 2005 ; St-Pierre et al., 2003 ; Mauger et al., 2015 ; Du Preez, 2000 ; DuPreez et al., 1994 ; Du Preez et al., 1990 ). A threshold of 65 was used for comparison reasons and sensitivity tests.…”

Section: Methodsmentioning

confidence: 99%

Influence of heat stress on milk production and its financial implications in semi-arid areas of South Africa

Ogundeji

Lakew

Tesfuhuney

et al. 2021

Heliyon

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Heat stress affects dairy cows' feed intake, reproductive system and milk production. This study analysed the financial implications of heat stress for small scale milk producers. The semi-arid regions of the Free State-Bloemfontein, Bothaville, and Bethlehem were selected for the study. To estimate the impact of heat stress on milk production, baseline (1950-1999) and mid-century (2040-2070) climate data and Temperature Humidity Index thresholds (THI thershold) of 70 and 65 were used. Mid-century data with no adaptation strategy resulted in a doubled loss, while moderate heat-mitigation strategies (wetting and forced ventilation) resulted in positive improvements in milk production and income of farmers. Results show strong polynomial correlations (R 2 of 0.73-0.79) between the T max and milk-production losses where above T max of 25 C, milk-production loss increased sharply. The combined average loss of milk production during the hot summer was estimated at 0.35 liters per cow in a day, which is equivalent to ZAR1.27 per cow per day. With changing climate, the highest revenue loss was recorded in the MPI_ESM_MR future climate scenario. Moreover, results from the questionnaires show that heat stress reduces farmers' milk production significantly in the summertime, and for most of the respondents, measures that should be taken are too costly to apply. Exhaustive analysis of the economic impacts of heat stress on milk production is recommended for future studies, as it is an important sector in alleviating household food insecurity in South Africa.

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Effect of heat stress on conception in a dairy herd model under South African conditions

Cited by 15 publications

References 9 publications

Influence of Heat Stress on the Cortisol and Oxidant‐Antioxidants Balance During Oestrous Phase in Buffalo‐Cows (Bubalus bubalis): Thermo‐protective Role of Antioxidant Treatment

Influence of Heat Stress on the Cortisol and Oxidant‐Antioxidants Balance During Oestrous Phase in Buffalo‐Cows (Bubalus bubalis): Thermo‐protective Role of Antioxidant Treatment

Heat Stress in Tunisia: Effects on dairy cows and potential means

Influence of heat stress on milk production and its financial implications in semi-arid areas of South Africa

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