Heat Processing of Protein Sources on the Faecal Excretion of Their Selenium in Dairy Cows

The aim of the study was to compare parameters of passage of nylon capsules and digesta represented by Cr-labelled maize silage through the digestive tract of dairy cows. The capsules were made of nylon cloth (42 µm pore size, 10 mm outside diameter) and applied orally. The evaluation was carried out in dairy cows with milk yield of 19.0 kg/day. The diet (17.6 kg DM/day) consisted of maize silage, lucerne hay and concentrate. Total mean retention time (TMRT), delay time (τ), summarised compartmental mean retention time (CMRTS), and mean individual compartmental retention times (CMRT1 and CMRT2) were calculated. TMRT, τ, CMRTS, CMRT1 and CMRT2 values of nylon capsules and Cr-labelled silage were 36.2 and 45.4 h (P < 0.01), 16.2 and 8.3 h (P < 0.01), 20.1 and 37.2 h (P < 0.01), 7.8 and 8.5 h, 12.2 and 28.7 h (P < 0.05), respectively. The calculated mean retention time of nylon capsules in the reticulo-rumen (CMRTS) was shorter and in the intestines (τ) was longer than that of digesta. For this reason the estimation of digestibility using the nylon capsule method can be questionable.  

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Lactational responses of dairy cows to changes in dietary protein fed at different stages of lactation

Proceedings of the British Society of Animal Production (1972) ◽

10.1017/s0308229600018018 ◽

1990 ◽

Vol 1990 ◽

pp. 17-17

Author(s):

Bethan L Wood ◽

D J Roberts ◽

E A Hunter

Keyword(s):

Body Weight ◽

Dairy Cows ◽

Dietary Protein ◽

Milk Protein ◽

Design Experiment ◽

Standard Diet ◽

Protein Sources ◽

Stage Of Lactation ◽

Milk Protein Content ◽

Ad Libitum

There is evidence from a range of experiments of increases in milk production, including improvements in milk protein content, to additional dietary inclusions of low degradability ‘animal’ protein sources. This experiment was designed to examine the effect of stage of lactation on the response of dairy cows to increased dietary protein.The continuous design experiment was conducted with 20 individually fed autumn calved dairy cows and four heifers over the first 26 weeks of lactation. The animals were fed initially a ‘standard diet’ of silage ad libitum and 8 kg (freshweight) of concentrate per day up to the 14th day of lactation. The cows were then allocated to four balanced groups of five cows (and one heifer) on the basis of lactation number, body weight and current milk yield. The data recorded during the first 14 days were used for subsequent covariance analysis.

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Effect of pelleting of concentrates on milk and blood selenium concentrations in lactating dairy cows when selenised yeast is included in the diet

Animal Production Science ◽

10.1071/an09161 ◽

2010 ◽

Vol 50 (6) ◽

pp. 371 ◽

Cited By ~ 4

Author(s):

C. R. Stockdale ◽

H. S. Gill

Keyword(s):

Dairy Cows ◽

Heat Processing ◽

Lactating Dairy Cows ◽

Holstein Friesian ◽

Friesian Cows

An experiment using 12 multiparous Holstein–Friesian cows was undertaken for 3 weeks in September–October 2008 to determine milk and blood selenium (Se) concentrations (surrogates for bioavailability) when Se-yeast was incorporated into pellets relative to providing unprocessed Se-yeast. The Se in the Se-yeast is principally in the form of seleno-methionine. Since the bioavailability of protein can be reduced by heat processing, it was hypothesised that the temperature and/or pressure conditions associated with commercial pelleting of concentrates would adversely influence the Se concentrations in milk and blood by reducing the bioavailability of Se in the animal compared with Se-yeast that had not been subjected to pelleting. The results clearly showed that pelleting conditions had no effect on concentrations of either milk or blood Se, thereby indicating that pelleting did not have an impact on the bioavailability of the Se in the animal.

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Effects of the ratio of effective rumen degradable protein to fermentable metabolizable energy on voluntary intake and milk yields of dairy cows

Proceedings of the British Society of Animal Science ◽

10.1017/s1752756200005664 ◽

2001 ◽

Vol 2001 ◽

pp. 184-184

Author(s):

A.R.J. Cabrita ◽

A.J.M. Fonseca ◽

C. Sampaio ◽

E. Gomes ◽

R.J. Dewhurst

Keyword(s):

Protein Synthesis ◽

Dairy Cows ◽

Metabolizable Energy ◽

Microbial Protein ◽

Maize Silage ◽

Protein Sources ◽

Microbial Protein Synthesis ◽

Voluntary Intake ◽

Production Response ◽

Degradable Protein

Diets with low ratios of effective rumen degradable protein (ERDP) to fermentable metabolizable energy (FME) are often offered to dairy cows in Portugal, because they are based on maize silage and protein sources are very expensive. It seems likely that this will restrict microbial protein synthesis and voluntary intake and, consequently, lead to reduced milk yields. The objective of this study was to examine the production response of dairy cows offered diets differing in ERDP/FME ratio.

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