Experiments on the nutrition of the dairy heifer: VIII. Effect on milk production of level of feeding at two stages of the lactation
01 Apr 1969-The Journal of Agricultural Science (Cambridge University Press)-Vol. 72, Iss: 02, pp 229-245
TL;DR: The higher level of feeding increased yields of milk and milk solids and solids-not-fat content in each period but had a smaller effect in mid- than in early lactation, a trend which was shown to continue further into later lactation.
Abstract: Eighty Friesian heifers were used to study the effect on milk production of two fixed levels of intake at two stages of the lactation. The rations were estimated to contain 7·9 and 6·2 kg starch equivalent per day, with adequate protein content. The heifers were allocated at random to these two levels of intake for weeks 1·9 of lactation and re-allocated at random to them for weeks 10–18 of lactation. Apart from minor variation the heifers were all fed alike for the remainder of the lactation.The higher level of feeding increased yields of milk and milk solids and solids-not-fat content in each period but had a smaller effect in mid- than in early lactation, a trend which was shown to continue further into later lactation. It also conserved body reserves.There was a residual effect in weeks 10–18 from the level of feeding in weeks 1–9 of lactation. This was directly additive to the effects of the current level of feeding. Those animals which had received the higher level of feeding in weeks 1–9 yielded more milk of higher solids-not-fat content than those which had had the lower level of feeding in weeks 1–9. The former group gained less live weight. The effect on milk production over the full lactation from additional feeding in early lactation was three times that observed in early lactation itself. Additional feeding in mid-lactation did not have a residual effect.The absolute output of milk per unit of food over the 18-week period was greatest for that group which had received the lower level of feeding throughout, followed by the group which received the higher level of feeding in weeks 1–9 only. This superiority was achieved at the expense of body reserves. There was a negative regression of live-weight change on milk production.Estimated intakes of metabolizable energy agreed closely with requirements for milk production as indicated by the Agricultural Research Council (1965).
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TL;DR: It is proposed that the fraction of cardiac output that perfuses the udder of lactating ruminants plays a role in regulation of nutrient partitioning between milk and body tissues and investigation of the mechanism of this response should prove fruitful to understanding causes of variations of milk production in response to feed quantity and quality.
144 citations
TL;DR: The effect of feed quality on the relationship between intake and stage of lactation in dairy cows was examined and significant interactions between total mixed diet and period were observed for DMI and milk yield, however, no significant residual effects of changing from one total mixed diets to the other were observed.
101 citations
TL;DR: Results indicate that all hormones measured and FFA responded to genetic selection for milk, and increases in GH are uniformly associated with increased genetic potential for milk yield.
Abstract: Plasma concentrations of prolactin (PRL), growth hormone (GH), insulin, glucagon, glucose, urea and free fatty acids (FFA) were measured in Holstein calves, yearlings, bred heifers and primiparous cows, either sired by bulls with high predicted differences (PD) for milk (selection group) or by bulls from an unselected random bred control population (control group; n = 6). Serial blood samples were collected before and after feeding for an 8-h period from 0900 to 1700 h. All animals were fed a complete feed at 1100 h and administered insulin (.6 IU/100 kg body weight) at 1400 h. Mean plasma PRL was greater in control animals after feeding and insulin administration, while GH was greater overall in selection cattle. Insulin remained elevated longer in selection animals after exogenous administration, and plasma glucagon was increased in the control group. While plasma glucose and urea were unaffected by genetic group, plasma FFA were elevated in selection group calves and primiparous cows compared with the control group. All hormones and metabolites differed among the pre- and post-feeding and insulin administration periods and also with age. Mean PRL and GH increased after feeding, while glucagon decreased after exogenous insulin. Plasma FFA declined after feeding, while urea and glucose were similar before and after feeding. Mean PRL increased and glucagon decreased with advancing age and plasma GH and insulin showed inverse relationships at different ages. Plasma FFA changes closely followed GH changes with age, while plasma glucose more closely followed insulin changes with age. Results indicate that all hormones measured and FFA responded to genetic selection for milk, and increases in GH are uniformly associated with increased genetic potential for milk yield.
99 citations
TL;DR: Results from this study indicate that offering a medium level of DHA (17 kg of herbage dry matter) in early lactation will increase milk production and offering concentrate will result in a linear increase in milk production.
92 citations
Cites background from "Experiments on the nutrition of the..."
...Themilksolidsconcentrationestablishedinearlylactation also appears to extend into later lactation ( Broster et al., 1969 )....
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...The milk solids concentration established in early lactation also appears to extend into later lactation (Broster et al., 1969)....
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TL;DR: This paper presents recent developments in describing this biological basis and evidence in support of the concepts involved as they relate to nutrient partitioning and the biological limitations of traditional evaluation of genotype × environment interactions and plasticity.
Abstract: Prediction of nutrient partitioning is a long-standing problem of animal nutrition that has still not been solved. Another substantial problem for nutritional science is how to incorporate genetic differences into nutritional models. These two problems are linked as their biological basis lies in the relative priorities of different life functions (growth, reproduction, health, etc.) and how they change both through time and in response to genetic selection. This paper presents recent developments in describing this biological basis and evidence in support of the concepts involved as they relate to nutrient partitioning. There is ample evidence that at different stages of the reproductive cycle various metabolic pathways, such as lipolysis and lipogenesis, are up or down regulated. The net result of such changes is that nutrients are channelled to differing extents to different organs, life functions and end-products. This occurs not as a homeostatic function of changing nutritional environment but rather as a homeorhetic function caused by the changing expression of genes for processes such as milk production through time. In other words, the animal has genetic drives and there is an aspect of nutrient partitioning that is genetically driven. Evidence for genetic drives other than milk production is available and is discussed. Genetic drives for other life functions than just milk imply that nutrient partitioning will change through lactation and according to genotype – i.e. it cannot be predicted from feed properties alone. Progress in describing genetic drives and homeorhetic controls is reviewed. There is currently a lack of good genetic measures of physiological parameters. The unprecedented level of detail and amounts of data generated by the advent of microarray biotechnology and the fields of genomics, proteomics, etc. should in the long-term provide the necessary information to make the link between genetic drives and metabolism. However, gene expression, protein synthesis etc, have all been shown to be environmentally sensitive. Thus, a major challenge in realising the potential afforded by this new technology is to be able to be able to distinguish genetically driven and environmentally driven effects on expression. To do this we need a better understanding of the basis for the interactions between genotypes and environments. The biological limitations of traditional evaluation of genotype £ environment interactions and plasticity are discussed and the benefits of considering these in terms of trade-offs between life functions is put forward. Trade-offs place partitioning explicitly at the centre of the resource allocation problem and allow consideration of the effects of management and selection on multiple traits and on nutrient partitioning.
90 citations
Cites background from "Experiments on the nutrition of the..."
...The substantial variation that can exist between individuals in their response to the same change in feeding is well documented (Kellner, 1926; Broster et al., 1969; Kirkland and Gordon, 2001a)....
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References
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Book•
01 Jan 1967
TL;DR: The energy metabolism of ruminants is studied in detail in the context of animal husbandry and its role in human health.
Abstract: The energy metabolism of Ruminants , The energy metabolism of Ruminants , مرکز فناوری اطلاعات و اطلاع رسانی کشاورزی
916 citations
Additional excerpts
...There was no effect on milk yield All animals fed according to Woodman (1957) standards Randomized block experiment on protein and energy requirements in lactation (Broster et al. 1969) All animals fed according to Woodman (1957) standards Randomized block experiment on sugar as a supplement for lactating cows (Anon....
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01 Jan 1948
107 citations
"Experiments on the nutrition of the..." refers background in this paper
...Blaxter (1967) reported a relationship R = 0-12Y, —0-40, where R is the response (kg per kg starch equivalent) to change in intake and Ys is the mean yield when the animal is fed according to standard rate (Woodman, 1957)....
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TL;DR: Campling et al. as mentioned in this paper investigated the relationship between the voluntary intake of roughage by cattle and the rate of disappearance of digesta from the reticule-rumen.
Abstract: The relationship between the voluntary intake of roughage by cattle and the rate of disappearance of digesta from the reticule-rumen was considered earlier (Campling, Freer & Balch, 1961, 1962). It was shown that the voluntary intake, by cows, of hay, oat straw or oat straw with urea was directly related to the rate at which digesta disappeared from the reticulo-rumen by digestion and absorption and by the onward passage of food residues. These findings have led us to investigate some of the factors that affect the passage of food residues from the reticulo-rumen, which include (a) the mean time of retention of food particles in the reticulo-rumen, and (b) the rate of flow of digesta from the reticulo-rumen to the omasum. Rate of passage, as measured by the mean retention time, and the rate of flow were defined by Balch (1961). The interrelationship of these two factors and the extent to which one can vary independently of the other have not previously been explored. I t was shown earlier (Campling et al. 1961, 1962) that the voluntary intakes of hay, oat straw and oat straw with urea were inversely related to the mean times of retention of food residues in the reticulo-rumen, even when the times of retention were measured at equal levels of intake. It seemed likely that factors affecting the rate at which food particles were reduced to a size suitable for transfer to the omasum would largely determine their mean time of retention in the reticule-rumen. The rate of digestion of food is clearly an important factor, but the extent and efficiency of mastication of food during the acts of eating and rumination may also be concerned. When a ruminant is established on any diet, the mean daily flow of organic matter from the reticulo-rumen to the omasum must equal the daily intake of food organic matter less the amount that disappears daily by absorption from the reticulo-rumen and by eructation of rumen gases. From the observations of Wester (1926), Schalk & Amadon (1928), Balch, Kelly & Heim (1951) and Stevens, Sellers & Spurrell(1960) it appears possible that the rate of flow of digesta from the reticulum to the omasum is related to the frequency of contraction of the reticulum and to the amount of digesta transferred to the omasum during each primary contraction of the reticulo-rumen. There was little previous evidence to suggest how these two factors vary in order to effect changes in the flow of digesta from the reticulo-rumen with different diets. Moreover, apart from the work of Balch (1952, 1958), there is little information on the
104 citations
TL;DR: The effects of stage of lactation and of age on milk and composition yield of cows kept under controlled conditions of feeding and management were investigated and characteristic changes were observed in the contents of total protein, and of the various protein fractions, and the major minerals of milk.
Abstract: The effects of stage of lactation and of age on milk and composition yield of cows kept under controlled conditions of feeding and management were investigated. Two groups each of 3 Friesian heifers were used: one group (A) was given a daily diet of 18 lb hay and concentrates at the rate of 3·8 lb/10 lb of milk and kept on experiment throughout the first 3 lactations; a second group (B) was given the same amount of hay and a constant daily amount of concentrates of 10·7 lb and was kept on experiment throughout the 1st lactation only.The total yields of milk and peak yields for the 1st lactation were similar in both groups. In all the cows, fat content was high early and late in lactation and varied little throughout the mid-lactation period. With cows of group A, the content of solids-not-fat declined until about the 5th week of lactation and then remained steady until a marked rise occurred late in lactation. With cows of group B, however, the content of solids-not-fat was at a minimum between the 5th and 10th weeks of lactation and then increased progressively until late lactation when a more marked rise occurred. Lactose content increased rapidly in the first few days of lactation and then remained constant for several months, eventually declining late in lactation. Characteristic changes were also observed in the contents of total protein, and of the various protein fractions, and of the major minerals of milk.The concentrations of all major constituents in milk secreted from the 2nd–5th months of lactation tended to decrease from lactation to lactation.The results are discussed in relation to the development of knowledge of the changes in milk composition throughout lactation.
70 citations