Substitution of crude cell wall for neutral detergent fibre in the equations of the Cornell Net Carbohydrate and Protein System that predict carbohydrate fractions: application to sunflower (Helianthus annulus L.)

Prediction of carbohydrate fractions using equations from the Cornell Net Carbohydrate and Protein System (CNCPS) is a valuable tool to assess the nutritional value of forages. In this paper these carbohydrate fractions were predicted using data from three sunflower (Helianthus annuus L.) cultivars, fresh or as silage. The CNCPS equations for fractions B(2) and C include measurement of ash and protein-free neutral detergent fibre (NDF) as one of their components. However, NDF lacks pectin and other non-starch polysaccharides that are found in the cell wall (CW) matrix, so this work compared the use of a crude CW preparation instead of NDF in the CNCPS equations. There were no differences in the estimates of fractions B, and C when CW replaced NDF; however there were differences in fractions A and B2. Some of the CNCPS equations could be simplified when using CW instead of NDF Notably, lignin could be expressed as a proportion of DM, rather than on the basis of ash and protein-free NDF, when predicting CNCPS fraction C. The CNCPS fraction B(1) (starch + pectin) values were lower than pectin determined through wet chemistty. This finding, along with the results obtained by the substitution of CW for NDF in the CNCPS equations, suggests that pectin was not part of fraction B(1) but present in fraction A. We suggest that pectin and other non-starch polysaccharides that are dissolved by the neutral detergent solution be allocated to a specific fraction (B2) and that another fraction (B(3)) be adopted for the digestible cell wall carbohydrates.

Prevalence of Rickettsia species antibodies and Rickettsia species DNA in the blood of cats with and without fever

Rickettsia species antibodies have been detected in some cats but it is unknown whether infected cats develop clinical signs. The prevalence of Rickettsia species deoxyribonucleic acid (DNA) in blood from clinically ill cats has not been determined. The objective of this study was to determine if cats with fever (body temperature >= 102.5 degrees F [39.2 degrees C]) were more likely to have evidence of rickettsial infection than healthy, age-matched, control cats with a body temperature < 102.5 degrees F. Rickettsia species polymerase chain reaction (PCR) assays were performed to detect rickettsial DNA extracted from blood (71 paired samples), indirect immunofluorescence assays (IFA) were performed to detect serum antibodies against Rickettsia felis (90 paired samples) and Rickettsia rickettsii (91 paired samples), and the results between pairs were compared. All samples were negative for Rickettsia species DNA. More cats with fever were seropositive for R felis or R rickettsii than control cats, but results were not statistically significant. Results of this pilot study failed to show an association between Rickettsia species DNA or Rickettsia species antibodies and fever. (c) 2008 ESFM and AAFP. Published by Elsevier Ltd. All rights reserved.

Differences in thermoregulatory ability between slick-haired and wild-type lactating Holstein cows in response to acute heat stress

Animals inheriting the slick hair gene have a short, sleek, and sometimes glossy coat. The objective of the present study was to determine whether slick-haired Holstein cows regulate body temperature more effectively than wild-type Holstein cows when exposed to an acute increase in heat stress. Lactating slick cows (n = 10) and wild-type cows (n = 10) were placed for 10 h in an indoor environment with a solid roof, fans, and evaporative cooling or in an outdoor environment with shade cloth and no fans or evaporative cooling. Cows were exposed to both environments in a single reversal design. Vaginal temperature, respiration rate, surface temperature, and sweating rate were measured at 1200, 1500, 1800, and 2100 h (replicate 1) or 1200 and 1500 h (replicate 2), and blood samples were collected for plasma cortisol concentration. Cows in the outdoor environment had higher vaginal and surface temperatures, respiration rates, and sweating rates than cows in the indoor environment. In both environments, slick-haired cows had lower vaginal temperatures (indoor: 39.0 vs. 39.4 degrees C; outdoor 39.6 vs. 40.2 degrees C; SEM = 0.07) and respiration rate (indoor: 67 vs. 79 breaths/min; outdoor 97 vs. 107 breaths/min; SEM = 5.5) than wild-type cows and greater sweating rates in unclipped areas of skin (indoor: 57 vs. 43 g.h(-1)/m(2); outdoor 82 vs. 61 g.h(-1)/m(2); SEM = 8). Clipping the hair at the site of sweating measurement eliminated the difference between slick-haired and wild-type cows. Results indicate that slick-haired Holstein cows can regulate body temperature more effectively than wild-type cows during heat stress. One reason slick-haired animals are better able to regulate body temperature is increased sweating rate.

Noradrenaline Involvement in the Negative-Feedback Effects of Ovarian Steroids on Luteinising Hormone Secretion

Noradrenaline has been shown to modulate the ovarian-steroid feedback on luteinising-hormone (LH) release. However, despite the high amount of evidence accumulated over many years, the role of noradrenaline in LH regulation is still not clearly understood. The present study aimed to further investigate the involvement of noradrenaline in the negative-feedback effect of oestradiol and progesterone on basal LH secretion. In experiment 1, ovariectomised (OVX) rats received a single injection of oil, oestradiol, or progesterone at 09.00-10.00 h and were decapitated 30 or 60 min later. Levels of noradrenaline and its metabolite, 3-methoxy-4-hydroxyphenylglycol (MHPG), were determined in microdissections of the preoptic area (POA) and medial basal hypothalamus-median eminence (MBH-ME) and correlated with LH secretion. Basal LH levels were decreased 30 and 60 min after oestradiol or progesterone injection, and this hormonal response was significantly correlated with a reduction in POA MHPG levels, which reflect noradrenaline release. In addition, noradrenaline levels in the POA were increased, whereas noradrenaline turnover (MHPG/noradrenaline ratio) was decreased 60 min after the injection of both hormones. No effect was found in the MBH-ME. In experiment 2, i.c.v. administration of noradrenaline (60 nmol), performed 15 min before oestradiol or progesterone injection in jugular vein-cannulated OVX rats, completely prevented the ovarian steroid-induced inhibition of LH secretion. The data obtained provide direct evidence that LH secretion in OVX rats is positively regulated by basal noradrenergic activity in the POA, and its reduction appears to play a role in the negative-feedback effect of ovarian steroids on LH secretion in vivo.