M. Rath

A comparison of different dairy cow breeds on a seasonal grass-based system of milk production: 1. Milk production, live weight, body condition score and DM intake

Abstract The objective of this study was to compare the performance of Dutch Holstein-Friesian (HF), upgraded Irish Holstein-Friesian (CL), French Montbeliarde (MB) and French Normande (NR) dairy cow breeds on a spring calving grass-based system of milk production. The HF cows produced the highest ( P P P P P P

The effect on milk production of replacing grass silage with maize silage in the diet of dairy cows

Abstract This experiment examined the effects of replacing high digestibility grass silage (GS) with maize silage (MS) grown under marginal climatic conditions on milk production and forage intake of Friesian cows. Fifty-six cows were fed 6 kg/d (fresh weight) of concentrates and one of four forages: (1) all GS, (2) 67:33 GS:MS, (3) 33:67 GS:MS, and (4) all MS. Concentrate crude protein (CP) level was varied to equalise total dietary CP. The analysis of the GS and MS were: DM (g/kg) 223 and 257, pH 3.91 and 3.98, and CP (g/kg DM) 155 and 91. The MS contained 219 g starch/kg DM. In vivo OM digestibilities were 0.782 and 0.674 (s.e.m.=0.0063, P P P P

The performance of Holstein Friesian dairy cows of high and medium genetic merit for milk production on grass-based feeding systems

The effect of cow genetic merit on the performance of spring calving Holstein Friesian dairy cows in first, second and third lactation was investigated. The study contained 96 first lactation animals in 1995, 96 second lactation animals in 1996, and 72 third lactation animals in 1997. Half of the animals were of high genetic merit (HG) and half of medium genetic merit (MG) for milk production. Genetic effects for the traits of interest were estimated as the contrast between the two genetic groups. The HG cows produced significantly higher yields of milk, fat, protein and lactose when compared to the MG cows. During the grazing season the HG cows had significantly ( , 0.001) higher grass DM intake (GDMI). In very early lactation when cows were indoors, offered grass silage ad libitum plus 7.9 kg of concentrate DM daily, there was no difference in DM intake. During the non-lactating period the HG cows had significantly (P , 0.01) higher silage DM intake (SDMI). Cow genetic merit had no significant effect on live weight with the exception of pre-calving weight at the beginning of second lactation when the HG cows had significantly (P , 0.05) higher live weight. At all stages of lactation the MG cows had significantly ( , 0.001) higher condition score. In early lactation the HG cows had greater (not significant) live weight loss and significantly (P , 0.05) greater condition score loss (indicating greater negative energy balance). In the dry period the HG cows had significantly (P , 0.01) greater live weight gain. The results of this study suggest that present day HG cows will produce high milk yields on a grass-based feeding system where an adequate quantity of high quality grass is available.

The nutritive value of palm kernel meal measured in vivo and using rumen fluid and enzymatic techniques

Abstract The objectives of this experiment were to determine the in vivo digestibility of solvent extracted and expeller palm kernel meal (PKM) and to establish how well this was predicted by laboratory techniques. Eight samples of expeller PKM and four samples of solvent extracted PKM were collected over 4 years. Their in vivo digestibility was measured by total faecal collection using four wethers per sample. The laboratory methods for predicting digestibility were the in vitro rumen fluid (RF), neutral detergent cellulase with gammanase (NCG), and pepsin cellulase with gammanase (PCG) methods. Gammanase has been added to the latter two methods specifically to improve the prediction of digestibility of PKM. The solvent extracted samples had higher organic matter digestibility (691 vs. 653 g/kg, sed 15.7) and crude protein digestibility (727 vs. 597 g/kg, sed 36.6). However, the expeller samples had higher ( P =0.12) contents of digestible energy (13.4 vs. 12.5 MJ/kg DM, sed 0.48) due to their higher gross energies (20.6 vs. 19.1 MJ/kg DM). None of the laboratory digestibility tests predicted digestibility satisfactorily. The residual standard deviation was 29, 32 and 31 g/kg for the RF, NCG and PCG methods, respectively. In particular, two expeller samples and two solvent extracted samples were grossly underpredicted by the laboratory methods. These results indicate that PKM is a medium quality energy feed for ruminants and that enzymatic procedures including gammanase or the in vitro rumen fluid method do not accurately predict its digestibility.

Estimation of genotype×environment interactions, in a grass-based system, for milk yield, body condition score, and body weight using random regression models

Abstract (Co)variance components for milk yield, body condition score (BCS), body weight (BW), BCS change and BW change over different herd-year mean milk yields (HMY) and nutritional environments (concentrate feeding level, grazing severity and silage quality) were estimated using a random regression model. The data analysed included records from 7478 multiparous upgraded Holstein–Friesian dairy cows. There were G×E interactions for BCS across all environments and for BW change across different concentrate levels and silage quality environments. There was a three-fold increase in the genetic standard deviation (S.D.) for BCS change to day 60 of lactation (CS60-5) and a doubling of the genetic S.D. for BCS at day 5 (CS5) as silage quality improved. The genetic variance for CS60-5 increased as concentrate level increased and as grazing severity became tighter. There was significant re-ranking of animals for milk yield, CS5 and CS60-5 over the different HMY environments; genetic correlations fell to −0.60 between extreme HMY environments for CS60-5 and were as low as 0.41 for CS5 across different HMY environments.

The effect of dietary protein content and hay intake level on the true and apparent digestibility of hay

The digestibility of concentrate feeds has been determined by difference using hay as a basal forage in many institutions. The objective of this experiment was to examine the effect of hay intake level and dietary crude protein (CP) content on hay digestibility. Groups of wether lambs (1 year old) were fed three levels (600, 700 and 800 g/day) of hay each at two CP contents (103 and 182 g CP/kg DM), achieved by using a urea solution. An extra group of lambs were fed hay unsupplemented with urea (42 g CP/kg DM) at a level of 800 g/day. The true organic matter digestibility (True OMD, calculated using two methods: True OMD 1 and 2) and apparent OMD of all treatments fed the 182 g CP/kg DM diets were significantly higher (P<0.05) than treatments fed the 103 g CP/kg DM diet (OMD: 632.8 g/kg vs. 604.2 g/kg; True OMD 1: 720.6 vs. 694.1 g/kg; True OMD 2: 711.8 vs. 681.0 g/kg). Apparent and true digestibility also increased as hay allowance increased and a significant linear effect was observed for GED. For the three groups fed 800 g/day of hay, significant differences in digestibility due to CP content only occurred between the 182 and the 42 g CP/kg DM diets (with the exception of CP digestibility). Although the effect of CP content was significant in some cases, the magnitude of the observed digestibility response is of little consequence for concentrate feed evaluation.

Intake, digestibility, milk production and kinetics of digestion and passage for diets based on maize or grass silage fed to late lactation dairy cows

Abstract This experiment compares maize and grass silage in relation to dry matter (DM) intake, milk production and the kinetics of digestion and passage for both forages. Twenty-two multiparous late lactation dairy cows were fed diets based on maize or grass silage (diets MS and GS, respectively) for a period of 7 weeks. Milk production was determined over 4 weeks ( n =11 per treatment) with total diet digestibility, forage DM intake and rumen outflow rate being determined in tie stalls ( n =7 per treatment). Forage degradability characteristics were determined using three fistulated steers. The difference in forage DM intake between treatments was highly significant ( P P >0.05). However, cows fed the MS diet had a significantly higher milk fat and milk protein content and milk fat yield ( P

The relationship between feeding level, rumen particulate and fluid turnover rate and the digestibility of soya hulls in cattle and sheep (including a comparison of Cr-mordanted soya hulls and Cr2O3 as particulate markers in cattle)

Abstract The aim of this work was to investigate the inter-relationships between feeding level, digestibility and rumen particulate and fluid turnover rate (k1p and k1f: % per hour) for high concentrate diets in cattle and sheep. In Experiment 1, four fistulated steers were used in a 4×4 Latin square experiment to determine k1p at high (12.45 kg/d) and low (6.48 kg/d) intakes using either Cr-mordanted soya hulls or Cr 2 O 3 as particulate markers. In the second and last period of this experiment, soya hulls digestibility and k1f were determined for each intake level. In Experiment 2, seven 1 year old wether sheep were used to determine the digestibility of soya hulls, k1p and k1f at high (907 g/d; n =3) and low (703 g/d; n =4) intakes. Increasing feeding level depressed DM, OM and GE digestibility ( P P P P P >0.10). For the pooled data set, linear relationships ( P P >0.05). These results indicate that depressions in digestibility at high feeding levels are associated with higher rumen turnover rates and that much of the variation in concentrate digestibility can be explained by changes in rumen turnover rate in both species.

An investigation of feeding level effects on digestibility in cattle for diets based on grass silage and high fibre concentrates at two forage: concentrate ratios

This experiment investigated the effect of feeding level on diet digestibility at two forage:concentrate ratios for diets containing grass silage. Four rumen fistulated Holstein–Friesian steers were used in a latin square experiment comprising a 2×2 factorial arrangement of treatments. Treatments were maintenance and 1.6×maintenance feeding level and 500 or 850 g of soya hulls/kg DM. Digestibility was determined by total collection, with fractional soya hulls (k1p) and fractional solute outflow rate (k1f) determined for the rumen using Cr-mordanted soya hulls and Co-EDTA, respectively. Rate of digestion was determined in-sacco. Increasing feeding level and soya hulls inclusion decreased diet DM, OM, CP, NDF, ADF and GE digestibility (P<0.01). The depression due to feeding level was greater for 850 g/kg DM soya hulls diets for GE (P<0.05), DM (P=0.06) and OM (P=0.06) digestibility. Rate of slowly degradable soya hulls DM and NDF digestion was lower (P<0.05 and P=0.07) for 850 g/kg DM soya hulls diets. Soya hulls k1p and k1f increased with feeding level but only the increase in k1f was significant (P<0.01). Diet OM, NDF and GE digestibility were positively related to rumen pH 6 h after feeding (P<0.01; R2=0.50 to 0.69). These results suggest that lower rumen pH values may be an important component of the larger digestibility depressions often observed for high concentrate diets.

Accuracy of predicting milk yield from alternative milk recording schemes

The effect of reducing the frequency of offi cial milk recording and the number of recorded samples per test-day on the accuracy of predicting daily yield and cumulative 305-day yield was investigated. A control data set consisting of 58 210 primiparous cows with milk test-day records every 4 weeks was used to investigate the infl uence of reduced milk recording frequencies. The accuracy of prediction of daily yield with one milk sample per test-day was investigated using 41 874 testday records from 683 cows. Results show that fi ve or more test-day records taken at 8-weekly intervals (A8) predicted 305day yield with a high level of accuracy. Correlations between 305-day yield predicted from 4-weekly recording intervals (A4) and from 8-weekly intervals were 0·99, 0·98 and 0·98 for milk, fat and protein, respectively. The mean error in estimating 305-day yield from the A8 scheme was 6·8 kg (s.d. 191 kg) for milk yield, 0·3 kg (s.d. 10 kg) for fat yield, and -0·3 kg (s.d. 7 kg) for protein yield, compared with the A4 scheme. Milk yield and composition taken during either morning (AM) or evening (PM) milking predicted 24-h yield with a high degree of accuracy. Alternating between AM and PM sampling every 4 weeks predicted 305-day yield with a higher degree of accuracy than either all AM or all PM sampling. Alternate AM-PM recording every 4 weeks and AM + PM recording every 8 weeks produced very similar accuracies in predicting 305-day yield compared with the offi cial AM + PM recording every 4 weeks.