Production characteristics of high-yielding dairy cows

Abstract

Understanding the relationships between food intake, milk output and body condition in high-yielding dairy cows is crucial in determining suitable management strategies. During two winter feeding periods 38 and 37 cows were individually fed, to appetite, complete diets which on average contained 11-7 MJ metabolizable energy per kg dry matter and comprised grass silage, concentrate meal and brewers' grains (draff). The groups' mean 305-day yield was 7 240 kg (s.d. 1 281) with 42 g (s.d. 4-3) fat per kg. Regression analysis was carried out to describe dry-matter intake both for 26 weeks post calving and for four successive 6-week periods from calving. The final equations, which had a residual s.d. of 0-07 to 0-10 of the observed intake, included milk yield, cow size and a measure of body-condition change. The cows were divided into three groups (high, medium and low) on two criteria: (1) mean milk yield (MJ/day) during the first 26 weeks of lactation and (2) post-calving backfat index determined ultrasonically. Differences were found between milk-yield groups from gross efficiency (milk yield (MJ)/ energy intake (MJ metabolizable energy)) (P < 0-001), mean metabolizable energy intake (MJ/day) (P < 0-01), dry-matter intake as a proportion of live weight (P < 0-05), and post calving live weight (kg) (P < 0-05). Differences were found between backfat-index groups for maximum backfat loss, and loss to day 42 (P < 0-001); also for mean live weight during the 26 weeks and post calving live weight (P < 0-001), dry-matter intake as a proportion of live weight (P < 0-05) and lactation number (P < 0-05). Interactions were found between the milk yield groups and backfat groups for milk yield (P < 0-01) and gross efficiency (F < 0-05) with the fattest group containing the highest and lowest yields and efficiencies.

Effects of Dairy Cow Genotype with Two Planes of Nutrition on Energy Partitioning Between Milk and Body Tissue

“…A few long-term studies have reported effects of genetic merit of dairy cows on energy partitioning between milk and body tissue. For example, studies published by Neilson et al (1983), Veerkamp et al (1994), and Veerkamp and Emmans (1995) reported differences in energy use of 2 Holstein-Friesian herds that were specially bred for high and low milk production. Dietary ME concentrations in these 3 studies were estimated from standard tabulated values for concentrates and in vitro nutrient digestibility for grass silages.…”

“…Total ME intake (weekly mean) for cows on the production study were then calculated from dietary ME concentrations (calorimetric measurements) and DM intake (production study). There is ample evidence to indicate that, within breed, high genetic merit cows have the ability to produce more milk energy than do low genetic merit cattle (Neilson et al, 1983;Grainger et al, 1985;Belyea and Adams, 1990;Gordon et al, 1995;Veerkamp and Emmans, 1995;Ferris et al, 1999), with similar effects being recorded between breeds (Holstein vs. Jersey cows; Tyrrell et al, 1990). In the present study, milk energy output was consistently higher with Holstein-Friesian than Norwegian cows during the whole lactation, irrespective of the plane of nutrition, although the difference was greater during early lactation and with the high concentrate diet.…”

Relationship between body condition scores and ultrasound measurements of subcutaneous fat and m. longissimus dorsi in dairy cows differing in size and type

“…Edmonson's system, being well documented and relatively easy to apply, became a quasi-standard. There exist several British studies (Garnsworthy and Topps, 1982;Neilson et al ., 1983;Garnsworthy and Jones, 1987;Garnsworthy, 1987) concerning BCS and ultrasound measurements, however they were not based on Edmonson's evaluation system. Faulkner et al .…”

Characterization of Na+, K+ ATPase in erythrocytes of dairy cows: Effect of diet and genetic selection for milk solids

“…The literature suggests that maintenance energy requirements (Taylor et al 1986) and the ability of an animal ro partition dietary energy between tissue reserves and milk synthesis vary between dairy cows of differing genetic potential for milk production (Neilson et al 1983). Evidence also indicates that it is possible to relate Na+, K+ ATpase (EC 3.6.1.3), often termed the sodium pump, to both these factors.…”

“…In dairy cattle it is known that low-producing cows partition more dietary energy toward body-fat synthesis during lactation in comparison with high-producing cows, which tend to direct dietary energy and energy from tissue reseryes toward milk synthesis (Neilson et al 1983). A relationship may therefore exist in dairy cows between Na+, K+ ATPase, degree of body fatness, and genetic merit for milk production.…”