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- Comparison between the effects of zilpaterol hydrochloride and
R-salbutamol fed during the finishing period on the growth and carcass
characteristics of feedlot cattle
Abstract: This study aimed to compare the effects of feeding 60 mg of the β-adrenergic agonist, zilpaterol HCl (Zilmax®), per steer per day versus feeding 120 mg of the β-adrenergic agonist, R-salbutamol (Salbutamate®10%), per steer per day for the last 30 days of the finishing period on the growth, efficiency, and carcass characteristics of 228 typical South African feedlot steers in a completely randomised control study. The steers were slaughtered at the same abattoir after a 3-day withdrawal period. The growth and feedlot parameters included starting mass, slaughter mass, average daily gain, live mass gain, and lean carcass gain. The carcass characteristics included warm (WCW) and cold carcass mass (CCW), carcass length (CL), subcutaneous fat thickness measured over the 13th rib (SCF), dressing percentage, carcass compactness, carcass classification score, age code, and fat code using the South African carcass classification system. The inclusion of zilpaterol HCl as a feed additive resulted in higher growth and efficiency, with an ADG of 1.3 kg/day (P
- Diagnosis and prognosis of bovine mastitis using ultrasonography and the
associated risk factors on dairy farms
Abstract: The study aimed to test whether the ultrasonographic morphometry and characteristic traits of udders and teats could be used to identify clinical mastitis in forty-eight adult Holstein-Friesian dairy cows. The inclusion and exclusion criteria were also declared with the help of the California Mastitis Test and Somatic Cell Count. Clinically, dairy cows (n = 48) were in their third lactation in order to undergo both ultrasonographic and phenotypic morphometry. Udder parenchyma as echotexture, teat width, teat width at the rosette of Furstenberg, teat cistern width, teat wall thickness, teat canal length, and ratios of TC/TWT, TWT/TW and TC/TW, as well as supramammary lymph node size, were evaluated, whereas phenotypic morphometric traits, i.e., udder circumference, udder depth, udder length, teat length, teat circumference, teat diameter, and the shortest distance from teat ends to floor were measured. There was substantial difference between morphological parameters of the teat such as, teat width, teat width at the rosette of Furstenberg, teat wall thickness, ratio of TC/TWT, ratio of TWT/TW, ratio TC/TW, teat canal length, echogenicity variables, and phenotypic morphometric traits, except for the teat cistern width. Pearson correlation indicated a strong correlation between lymph node length and lymph node width. Clinical mastitis in cattle is related to udder and teat morphometric traits. Incorporating these characteristics into the selection and breeding programme may aid in the selection of animals for mastitis resistance. Ultrasound is an effective imaging and morphological assessment tool for the diagnosis and prognosis of clinical mastitis in dairy cows.
- Effects of dietary supplementation with yeast chromium or dihydropyridine
on milk composition and serum biochemical indices of periparturient dairy
cows under heat stress
Abstract: The objective of the current study was to evaluate the effects of dietary supplementation with chromium yeast (Cr-yeast) and dihydropyridine (DHP) on nutrient utilization, milk composition, and antioxidative status of prepartum dairy cows under heat stress. Twenty-four perinatal dairy cows (600 ± 14 kg; parity 2-3) were divided into three groups and fed the same basal diet with no supplement (control group), 8 g of Cr-yeast (Cr-yeast group), or 3 g of DHP (DHP group) per day. The experimental period consisted of a 7-d adaptation period and a 30-d data collection period from day 27 prepartum to day 3 postpartum. The temperature humidity index (THI) observed at daytime during the trial period exceeded 72, and the mean daily THI was 79.43. Norepinephrine in the Cr-yeast group decreased in prepartum cows. Serum cortisol in Cr-yeast or DHP group cows was lower in the postpartum period than in the control; however, serum cortisol levels decreased in the DHP group in the prepartum period. Dietary supplementation with Cr-yeast increased the digestibility of ether extract and the concentration of milk fat, while the solid non-fat (SNF) level was reduced. In the DHP group, the lactoprotein content was higher than the control. Total antioxidant capacity (T-AOC) was higher and the malondialdehyde (MDA) content tended to increase before calving in the Cr-yeast and DHP groups. Dietary supplementation with Cr-yeast or DHP can relieve the adverse impact caused by heat stress in prepartum dairy cows.
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Open Access journal
