ABSTRACT
This study approached the relationships between heat stress and metabolic and milk parameters in a commercial herd of Holstein cows located in southern Brazil. A total of 50 multiparous cows at different lactations and lactation stages were selected in order to obtain 450 samples during two consecutive years (2011 and 2012). The animals were fed a partial mixed ration along with ryegrass pasture in a semi-confinement system. Blood, milk, and urine samples were taken during the summer and winter for a total of eight samples. Three intervals of temperature-humidity index (THI) were established during the summer months (January and February) as follows: low group (LOW), THI between 75 and 81 (N = 100); moderate group (MOD), THI between 81 and 82 (N = 150); and severe group (SEV), THI between 83 and 90 (N = 150). The group of cows sampled during winter (July) constituted the control group (CON; THI = 59, N = 50). Increased total protein, albumin, glucose, and cholesterol occurred in heat-stressed cows. Increased AST activity was also observed in heat-stressed cows, but triglycerides and beta-OH-butyrate did not show any difference among groups. Lower lactate and higher pO2 were seen in cows with heat stress than CON. Cows in SEV had a 21 % milk yield decrease, while lactose and protein decreased with fat not being affected. Heat stress had strong effects on metabolic, clinical, and performance parameters in Holstein cows.
Subject(s)
Cattle Diseases/physiopathology , Heat Stress Disorders/veterinary , Milk/metabolism , Animal Husbandry , Animals , Brazil , Cattle , Dairying , Female , Heat Stress Disorders/blood , Heat Stress Disorders/physiopathology , Hot Temperature , SeasonsABSTRACT
The nucleotide and deduced amino acid sequences of the actins from ticks, Boophilus microplus, Haemaphysalis longicornis and Rhipicephalus appendiculatus, have been determined. Nucleotide sequence analysis showed open reading frames of 1128-nucleotide-long encoding proteins of 376 amino acids with a predicted molecular weight of 41.82 kDa each. Comparison between the nucleic acid and deduced amino acid sequences as well as structural and phylogenetic analyses of these genes confirmed the high similarity among actins from ticks in comparison to other species.
Subject(s)
Actins/genetics , DNA, Complementary/chemistry , Ixodidae/genetics , Actins/chemistry , Actins/isolation & purification , Amino Acid Sequence , Animals , Base Sequence , Cloning, Molecular , DNA, Complementary/genetics , Female , Ixodidae/classification , Male , Molecular Sequence Data , Molecular Weight , Phylogeny , Reverse Transcriptase Polymerase Chain ReactionABSTRACT
Efforts are being undertaken to control tick infestations that cause important economic losses. A cathepsin L-like endopeptidase of Boophilus microplus was expressed in Escherichia coli; the recombinant enzyme was capable of hydrolysing gelatin, tick vitellin and bovine haemoglobin. In this paper we focus on the expression and local of synthesis of this enzyme in the tick. RT-PCR experiments showed that this endopeptidase is transcribed in the gut of partially engorged tick females. In immunoblotting, polyclonal antibodies against the recombinant enzyme reacted with proteins of larvae older than 5 days, of fully and partially engorged female gut. In immunolocalization experiments the enzyme was localized in probable secretory cells of the gut. Based on our findings we postulate that BmCL1 may be involved in haemoglobin degradation in the B. microplus gut. This enzyme may be used as target for the control of this parasite.
