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Global warming is a major challenge to the sustainable and humane production of food because of the increased risk of livestock to heat stress. Here, the example of the prolactin receptor (PRLR) gene is used to demonstrate how gene editing can increase the resistance of cattle to heat stress by the introduction of mutations conferring thermotolerance. Several cattle populations in South and Central America possess natural mutations in PRLR that result in affected animals having short hair and being thermotolerant. CRISPR/Cas9 technology was used to introduce variants of PRLR in two thermosensitive breeds of cattle – Angus and Jersey. Gene‐edited animals exhibited superior ability to regulate vaginal temperature (heifers) and rectal temperature (bulls) compared to animals that were not gene‐edited. Moreover, gene‐edited animals exhibited superior growth characteristics and had larger scrotal circumference. There was no evidence for deleterious effects of the mutation on carcass characteristics or male reproductive function. These results indicate the potential for reducing heat stress in relevant environments to enhance cattle productivity. [ABSTRACT FROM AUTHOR]

The objective of this study was to assess aspects of the social behavior of a mixed-breed herd of beef cows as a potential source for stress and economic losses. Angus (AN; N = 10), Brahman (BR; N = 10), and Senepol (SE; N = 10) cows were assigned to two groups (N = 15 each containing equal breed numbers) on separate pastures. Agonistic interactions (win/loss) during feeding were recorded daily for 45 days. Dominance values were estimated as the proportion of individuals dominated to total herdmates. From this, individuals were placed into social categories based upon linear ranking as follows: dominants (D), intermediate (I), and subordinates (S). Breed influenced (P < 0.01) social category, with SE cows being dominants (P < 0.05) over AN and BR cows. Interactions between AN and BR cows were less (P < 0.0005) than interactions between AN and SE (53 vs 140, respectively). Within breeds, BR (152) and SE (182) cows had more (P < 0.0005) agonistic interactions than AN (107) cows. Although apparently influenced by breed, agonistic interactions occurred more frequently (P < 0.005) between social categories than within social categories (814 vs 310, respectively). Dominant cows were involved in more agonistic interactions with cows from different social categories than were intermediate and subordinate cows (P < 0.0005). However, intermediate (100) and subordinate (157) cows generated more (P < 0.0005) agonistic interactions within their own social category than dominant cows (53). It was concluded that, in mixed-breed herds, breed influences both social organization and agonistic interactions which could be considered as potential sources of stress and economic losses. [ABSTRACT FROM AUTHOR]

The article explains the role of lymphatic fluid in screening Mycobacterium avium subspecies paratumberculosis (MAP) in cattle. The study was performed on 58 cows, where lymph fluid was extracted from their udders to identify traces of MAP through nested polymerase chain reaction. Results revealed that MAP was identified in 43.1 percent of lymph samples, where it was discovered in 66.7 percent cows with clinical Johne's disease.

The objectives of this study were to estimate the prevalence of herd and individual bull infection with Tritrichomonas foetus in a survey of beef bulls in the state of Florida and to perform an epidemiological investigation of risk factors for the disease. Bulls were tested for T. foetus colonization by a single preputial scraping and culture. Bull infection prevalence within herds was calculated and relationships with bull, herd factors, and production measurements were determined. The survey included 1984 beef bulls in 59 herds throughout Florida; nine bulls in three small herds (<100 cows) were later excluded from the models. An overall prevalence for T. foetus-infected bulls was 6.0% (within-herd prevalence ranged from 0 to 27%). The herd prevalence was 30.4% (i.e. at least one infected bull); infected bulls were found in 11.1 and 39.5% of herds sampled in North and South Florida, respectively. The likelihood of disease was greatest in larger herds in more extensive management settings (≥500 cows, 53.9% prevalence; medium-sized herds of 100–499 cows, 10.0% prevalence). Tritrichomonas foetus infection was associated with several bull factors, including age, breed, herd, and herd management practices (bull-to-cow ratio, bulls per breeding group). Tritrichomonas foetus infection continues to be prevalent in beef herds in Florida that use natural service. [Copyright &y& Elsevier]

Abstract: Paratuberculosis represents a major problem in farmed ruminants and at the present is considered a potential zoonosis. The disease is caused by Mycobacterium avium subsp. paratuberculosis, and susceptibility to infection is suspected to have a genetic component. Caspase recruitment domain 15 (CARD15) gene encodes for a cytosolic protein implicated in bacterial recognition during innate immunity. Crohn''s disease (CD) is an idiopathic inflammatory bowel disease in humans comparable in many features to bovine paratuberculosis involving an abnormal mucosal immune response. The association between mutations in the CARD15 gene and increased risk of Crohn''s disease has been described. The objective of this candidate gene case-control study was to characterize the distribution of three polymorphisms in the bovine CARD15 gene and test their association with paratuberculosis infection in cattle. Three previously reported single nucleotide polymorphisms (E2[-32] intron 1; 2197/C733R and 3020/Q1007L) were screened for the study population (431 adult cows). The statistical analysis resulted in significant differences in allelic frequencies between cases and controls for SNP2197/C733R (P <0.001), indicating a significant association between infection and variant allele. In the analysis of genotypes, a significant association was also found between SNP2197/C733R and infection status (P <0.0001); cows with the heterozygous genotype were 3.35 times more likely to be infected than cows with the reference genotype (P =0.01). Results suggest a role for CARD15 gene in the susceptibility of cattle to paratuberculosis infection. These data contribute to the understanding of paratuberculosis, suggest new similarities with Crohn''s disease and provide new information for the control of bovine paratuberculosis. [Copyright &y& Elsevier]

Genetic, social and environmental factors affecting behavioral estrus were evaluated in Angus (n=10), Brahman (n=10) and Senepol (n=10) cows during a PGF2α synchronized estrus and subsequent spontaneous estrus. Cows were equally stratified by breed to two groups of 15. Both groups were pre-synchronized with a modified two-injection PGF2α protocol. At the start of the experiment, cows were treated with 25 mg PGF2α followed by a second and third administration of 12.5 mg PGF2α, 11 and 12 days later to induce synchronized estrus. The subsequent estrus was designated as spontaneous estrus. Behavioral estrus data including the onset and end of estrus, estrous duration and the total number of mounts received for the synchronized and spontaneous estruses were collected using HeatWatch®. Interval from the third PGF2α treatment to the onset of a HeatWatch® estrus occurred earlier (P<0.05) in Angus (31±5 h) than Brahman (53±7 h) or Senepol (53±4 h) cows, with dominant Senepol and Brahman cows taking longer to exhibit estrus after PGF2α than subordinate cows. The duration of the synchronized estrus tended to be shorter (P<0.06) in Senepol (12±3 h) than in Angus (19±2 h) or Brahman (17±2 h) cows. Behavioral estrus data between the two periods were confounded by greater temperature–humidity index (THI) values during spontaneous estrus. The THI during spontaneous estrus appeared (P=0.09) to affect the duration of estrus (9±1 h versus 16±1 h) and did affect (P<0.0001) the total number of mounts received (8±4 mounts versus 34±4 mounts) during spontaneous estrus compared to synchronized estrus. Breed had no effect (P>0.10) on the duration and total number of mounts received during synchronized and spontaneous estruses. In conclusion, type of estrus (synchronized or spontaneous), THI, social dominance and breed exerted significant effects on characteristics associated with behavioral estrus in beef cattle in subtropical environments. [Copyright &y& Elsevier]