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Responses to starch infusion on milk synthesis in low yield lactating dairy cows
The effect of starch infusion on production and metabolic parameters was investigated in low yield lactating cows from 86 days in lactation. Six Holstein cows fitted with permanent ruminal cannulas were arranged into two complete 3 × 3 Latin squares, infused a starch solution containing 800 grams starch for 16 days. The three treatments were: (1) ruminal and abomasal infusion with water (Control); (2) ruminal infusion with cornstarch solution and abomasal infusion with water (Rumen); (3) ruminal infusion with water and abomasal infusion with cornstarch solution (Abomasum). There was no significant difference (P > 0.05) among the three treatments with low yield lactating cows in dry matter intake, body condition and milk yield, and milk component concentrations. However, cows receiving starch through rumen performed better than through abomasum directly during the glucose tolerance test procedure with higher area under the curve (AUC; P = 0.08) and shorter half-time (t1/2; P= 0.11) of plasma insulin, therefore, it increased glucose disposal, which stated a lipid anabolism other than mobilization after energy supplementation. In conclusion, extra starch infusion at concentration of 800 g/d did not ameliorate energy supplies to mammary gland and improve the lactating performance as we expected, but resulted in a tendency of shifting metabolic event toward the pathway of subcutaneous adipose accumulation at low yield lactating cows.
Keywords: starch infusion, lactation performance, glucose tolerance test
Effects of starch infusion with 800 g/d on performance, production and glucose tolerance test in lactation dairy cows |
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Items |
Treatment |
Pooled |
Contrast |
|||
Control |
Rumen |
Abomasum |
SEM |
Infusion |
Site |
|
Dry matter intake, kg/d |
18.58 |
17.96 |
17.67 |
0.30 |
0.26 |
0.70 |
Body weight, kg |
584.5 |
590.5 |
600.7 |
8.35 |
0.55 |
0.63 |
Body condition score |
2.71 |
2.75 |
2.79 |
0.06 |
0.64 |
0.79 |
Backfat thickness, mm |
17.50 |
19.33 |
19.87 |
0.61 |
0.37 |
0.83 |
| Milk yield, kg/d | 21.05 |
21.02 |
21.07 |
0.28 |
0.99 |
0.93 |
Milk fat, % |
3.43 |
3.42 |
3.35 |
0.03 |
0.43 |
0.25 |
Milk protein, % |
2.88 |
2.91 |
2.88 |
0.02 |
0.71 |
0.56 |
Milk lactose, % |
4.93 |
4.98 |
4.94 |
0.03 |
0.70 |
0.62 |
Insulin resistance |
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Basal concentration, μIU/mL |
18.4 |
16.5 |
18.7 |
1.88 |
0.83 |
0.79 |
Peak concentration, μIU/mL |
30.3 |
27.7 |
41.4 |
1.36 |
0.91 |
0.62 |
Clearance rate, %/min |
3.64 |
2.59 |
5.83 |
0.65 |
0.90 |
0.83 |
Area under the curve, μIU × min/mL |
347.8 |
333.8 |
374.5 |
17.59 |
0.81 |
0.08 |
t1/2, min |
19.1 |
26.7 |
13.6 |
3.14 |
0.97 |
0.11 |