Quantity of digesta in the reticulo-rumen of cows differing in susceptibility to bloat

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Lactating cows were chosen for high or low susceptibility to bloat from within herds bred for high (HS) and low susceptibility (LS) for about three generations. For 4 experimental weeks they were allocated to a latin-square change-over design consisting of four feed treatments. The treatments were one of ad libitum hay and three levels of a lucerne diet -15 kg or 30 kg fresh material per day or ad libitum. Eight cows per herd were used, two per herd being allotted each week to each feed treatment. The objective was to compare HS and LS cows for food intake, empty liveweight, bloat score, heart girth, rib girths before and after feeding, saliva proteins, and three blood components. HS cows were 41 kg (12.1070) lighter than LS cows and 7.5 cm (4.5070) smaller in heart girth. Pre-feeding rib girths were not significantly different. However, adjusting the pre-feeding rib girths for heart girth by linear regression, the rib girths were respectively 193.7 and 187.8 em, a difference of 3.1 % (P< 0.06). There was no bloat among cows on the hay diets. The HS cows could bloat on 15 kg of lucerne, so that high intakes were not required, whereas the LS cows consumed up to 30 kg of lucerne with little effect. Mean bloat scores on lucerne (0 -4 scale) averaged 1.03 for HS and 0.11 for LS cows. Differences in post-feeding 1 Deceased Received 22 July 1987; accepted 3 March 1988 rib girths were affected by differences in intake and in bloat; for a unit increase in rib girth in HS cows as a result of food intake there was an additional increase of 0.77 as a result of bloat. The ratio of rib girth increase to dry matter (DM) intake was significantly higher in the HS cows (5.64 cm/kg) than the LS cows (3.20 cm/kg). The correlations of bloat score with heart girth, pre-feeding rib girth, and post-feeding rib girth were -0.32,0.19, and 0.41, and the best linear combination of the first two girths had a correlation of 0.63 with bloat score. The HS cows produced significantly lower daily yields of milk and milkfat. Saliva volumes were obtained by front and rear sampling bits from cows after feeding. There was a significant difference between herds in the ratio of rear to front saliva volumes. Twelve saliva band concentrations were assayed and results from front saliva in HS cows were significantly higher than for LS cows on lucerne diets, and vice versa on hay. There were no significant differences between herds in sodium (Na) or potassium (K) concentration from rear saliva and packed cell volume, nor in protein and albumin concentrations in plasma. However, in one of the two sampling schedules the ratio of Na to K was significantly lower in HS than LS cows.

Section: Front Salivasupporting

confidence: 76%

Genetics of susceptibility to bloat in cattle IV. Girth measurements, bloat scores, saliva proteins, blood components, and milk production, liveweight, and intake data

McIntosh¹,

Morris²,

Cockrem³

et al. 1988

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“…However, although the major determinant of apparent digestibility of a diet is its apparent digestibility in the rumen (Ulyatt et al 1967), reduced digestion in the reticulo-rumen may be compensated for by increased digestion in the lower tract (Ulyatt et al 1967;Grovum & Williams 1977). Aspects of digestibility and retention of digesta in the reticulo-rumen are investigated in a subsequent paper (Carruthers et al 1988).…”

Section: Discussionmentioning

confidence: 99%

Food intake, milk production, and digestive efficiency of cows differing in susceptibility to bloat

Carruthers¹,

Bryant²,

Cockrem³

et al. 1988

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Voluntary food intakes of 16 high (HS) and 16 low (LS) bloat-susceptible dairy cows were established when they were offered pasture or hay while pregnant but not lactating and when they were offered pasture or 751170 pasture 25% hay while lactating. Each experiment consisted of two 21-day periods with eight HS and eight LS cows on each diet in each period, cows changing diets between periods. Digestibility of the diets and complete energy balances were obtained using, respectively, three and one cow of each susceptibility group per diet per period. There were no significant differences between susceptibility groups in voluntary intake when expressed on a Iiveweight basis, in apparent digestibility of dry matter (DM), organic matter (OM), nitrogen (N), or energy (E), or in partitioning of E and other nutrients. LS cows produced more milk than HS cows but yields of fat, protein, and lactose were similar for both susceptibility groups.

“…Methods for removal of digesta and sampling of DM and fluid have been described by Carruthers et al (1988). Table 4 Calculated net losses (kg) of fluid, DM, and total digest a from reticulo-rumen during feeding and at intervals after feeding for cows offered diets of high (HR) and low (LR) K : Na ratio.…”

Section: Faeces and Urinementioning

confidence: 99%

“…Calculations and statistical analysis Net fluid, DM, and total digesta losses were calculated from weights of digesta returned and subsequently removed, as described by Carruthers et al (1988), and using the time intervals of a 150-min feeding period and post-feeding periods of 420 min (0 -7 h) and 870 min (7 -21.5 h).…”

Section: Faeces and Urinementioning

confidence: 99%

“…Variations in Na and K intake can have marked effects on electrolyte and fluid absorption from digesta, fluid outflow from the reticulo-rumen, and metabolism of Na and K by the kidney (Warner & Stacy 1972). The quantity of digesta in the reticulo-rumen is a factor which may contribute to the susceptibility of an animal to bloat, animals of low susceptibility having less digesta than those of high susceptibility (Carruthers et al 1988).…”

Section: Introductionmentioning

confidence: 99%

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Quantity and composition of digesta in the reticulo-rumen of cows offered two diets differing in K:Na ratio

Carruthers¹,

Bryant²

1988

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Pasture diets of high potassium (K) : sodium (Na) ratio (HR) or low K : Na ratio (LR) were offered for 2 h each day to eight rumenfistulated cows that were neither lactating nor pregnant. Dry matter (DM) intake averaged 4.47 kg per cow per day. Na and K intakes were, respectively, 9 g and 176 g on the HR diet and 21 g and 142 g on the LR diet. Offering the LR diet was associated with an increased Na concentration and decreased K concentration in rumen fluid both before and after feeding, an increased quantity of digest a in the reticulo-rumen, and a decreased apparent digestibility of the diet, compared to the HR diet. The net inflow of fluid to the reticulorumen and outflow to the omasum were higher on the LR diet than on the HR diet during 7 h after feeding. The K concentration in saliva was lower and the packed cell volume of blood higher in cows when offered the LR diet. The mechanism by which diets of low K: Na ratio may affect bloat is discussed.