Site of Digestion of Starch in the Gastrointestinal Tract of Dairy Cows and Its Effect on Milk Yield and Composition

In sheep production systems based on extensive grazing, neonatal mortality often reaches 15% to 20% of lambs born, and the mortality rate can be doubled in the case of multiple births. An important contributing factor is the nutrition of the mother because it affects the amount of colostrum available at birth. Ewes carrying multiple lambs have higher energy requirements than ewes carrying a single lamb and this problem is compounded by limitations to voluntary feed intake as the gravid uterus compresses the rumen. This combination of factors means that the nutritional requirements of the ewe carrying multiple lambs can rarely be met by the supply of pasture alone. This problem can overcome by supplementation with energy during the last week of pregnancy, a treatment that increases colostrum production and also reduces colostrum viscosity, making it easier for the neonatal lamb to suck. In addition, litter size and nutrition both accelerate the decline in concentration of circulating progesterone that, in turn, triggers the onsets of both birth and lactogenesis, and thus ensures the synchrony of these two events. Furthermore, the presence of colostrum in the gut of the lamb increases its ability to recognize its mother, and thus improves mother-young bonding. Most cereal grains that are rich in energy in the form of starch, when used as supplements in late pregnancy will increase colostrum production by 90% to 185% above control (unsupplemented) values. Variation among types of cereal grain in the response they induce may be due to differences in the amount of starch digested post-ruminally. As a percentage of grain dry matter intake, the amount of starch entering the lower digestive tract is 14% for maize, 8.5% for barley and 2% for oats. Supplements of high quality protein from legumes and oleiferous seeds can also increase colostrum production but they are less effective than cereal grains. In conclusion, short-term supplementation before parturition, particularly with energy-rich concentrates, can improve colostrum production, help meet the energy and immunological requirements for new-born lambs, and improve lamb survival.

Section: Levels Of Energymentioning

confidence: 99%

Section: Levels Of Energymentioning

confidence: 99%

Colostrum production in ewes: a review of regulation mechanisms and of energy supply

Banchero

Milton

Lindsay

et al. 2015

“…Barley starch is reported to be degraded rapidly and is associated with the rapid production and absorption of metabolites in the rumen of dairy cows (Nocek and Tamminga, 1991;Silveira et al, 2007), both of which can be indicative for metabolic intake regulation. The rumen fermentation rate of maize starch is slower than that of barley (Nocek and Tamminga, 1991;Mills et al, 1999;Tothi et al, 2003), which can reduce the rate of metabolite absorption. Moreover, the degradation of maize starch may be so slow that it does not completely undergo fermentation in the rumen (McCarthy et al, 1989) and is instead digested post-ruminally or excreted in faeces.…”

Section: Introductionmentioning

confidence: 99%

The effects of and interactions between the maturity of grass silage and concentrate starch source when offered as total mixed rations on the performance of dairy cows

Tahir

Lund

Hetta

2013

A 2 3 2 factorial feeding experiment was conducted to examine the effects of varying the maturity level of the grass used to prepare silage and the nature of concentrate starch source and their interactions on dry matter intake (DMI), diet digestibility, energy corrected milk (ECM) production and milk composition in dairy cows. Twenty-eight multiparous Swedish Red dairy cows, 133 6 45 days in milk (DIM), with an average milk yield of 30 6 4 kg/day and a live weight of 624 6 69 kg were blocked by DIM and randomly assigned to seven replicated balanced 4 3 4 Latin squares with four 21-day experimental periods. The experimental diets consisted of four total mixed rations (TMR) consisting of early-cut grass silage (EGS) supplemented with either barley-or maize-based concentrate and late-cut grass silage (LGS) supplemented with either barley-or maize-based concentrate. All TMR contained identical proportions of forage (51%) and concentrate (49%). Total tract digestibility was estimated by determining indigestible NDF (iNDF) concentrations in feeds and faeces and using iNDF as an internal marker. The feeds' ruminal degradation parameters were determined using both in situ (nylon bag) and in vitro (gas production (GP)) techniques. Cows offered diets containing EGS had greater (P , 0.001) daily dry matter (DM) intakes, ECM yields and total tract digestibilities for DM and organic matter (OM), but these were not affected by the nature of the concentrate starch source. No interaction between the maturity of the silage and the nature of the concentrate starch source was observed for DMI, diet digestibility or ECM yield. Both grass silages and concentrates had similar rates of ruminal degradation of NDF when measured in situ. The in situ DM (P , 0.001) and starch (P 5 0.001) degradation rates of barley-based concentrate were greater than those for maize-based concentrate. In vitro OM GP rates and extents were similar for both concentrate feeds. The results showed that diets containing EGS offered better animal performance and diet digestibility than diets containing LGS. The concentrate starch source did not affect animal performance, but total NDF digestibility was better with diet containing barley-than maize-based concentrate.

“…In practical terms, this has been accomplished mainly through the addition of starch rich feed ingredients. Perceived benefits of feeding starch include increased metabolizable energy and metabolizable protein supply per unit of feed intake and thus greater milk and milk protein yield compared with feeding fibre, although there is no clear evidence as to the advantages of postruminal digestion of starch to enhance milk yield or to change milk composition compared with ruminal digestion of starch (Nocek and Tamminga, 1991). Starch digestion site is important for calculating the total fermentable carbohydrate supply to the rumen, which is relevant for managing rumen fermentation level, or potentially acidosis.…”

Section: Introductionmentioning

confidence: 99%

Estimation of the in situ degradation of the washout fraction of starch by using a modified in situ protocol and in vitro measurements

Jonge

Laar

Dijkstra

2015

The in situ degradation of the washout fraction of starch in six feed ingredients (i.e. barley, faba beans, maize, oats, peas and wheat) was studied by using a modified in situ protocol and in vitro measurements. In comparison with the washing machine method, the modified protocol comprises a milder rinsing method to reduce particulate loss during rinsing. The modified method markedly reduced the average washout fraction of starch in these products from 0.333 to 0.042 g/g. Applying the modified rinsing method, the fractional degradation rate ( k d ) of starch in barley, oats and wheat decreased from on average 0.327 to 0.144 h −1 whereas for faba beans, peas and maize no differences in k d were observed compared with the traditional washing machine rinsing. For barley, maize and wheat, the difference in non-fermented starch in the residue between both rinsing methods during the first 4 h of incubation increased, which indicates secondary particle loss. The average effective degradation of starch decreased from 0.761 to 0.572 g/g when using the new rinsing method and to 0.494 g/g when applying a correction for particulate matter loss during incubation. The in vitro k d of starch in the non-washout fraction did not differ from that in the total product. The calculated ratio between the k d of starch in the washout and non-washout fraction was on average 1.59 and varied between 0.96 for oats and 2.39 for maize. The fractional rate of gas production was significantly different between the total product and the non-washout fraction. For all products, except oats, this rate of gas production was larger for the total product compared with the non-washout fraction whereas for oats the opposite was observed. The rate of increase in gas production was, especially for grains, strongly correlated with the in vitro k d of starch. The results of the present study do not support the assumption used in several feed evaluation systems that the degradation of the washout fraction of starch in the rumen is much faster than that of the non-washout fraction.Keywords: particulate matter loss, in situ protocol, in vitro, rumen degradability, starch ImplicationThis study showed that the fractional degradation rate (k d ) of starch of the washout fraction was lower than generally assumed. In addition, the rinsing method affected the k d caused by particulate matter loss. The effect of both observations on the effective degradation of starch varied between feed ingredients, and can therefore change the ranking in nutritive value.