In 1920 August Thienemann, a German freshwater biologist, introduced the concept of trophic, or feeding, levels (see trophic level), by which the energy of food is transferred through a series of organisms, from green plants (the producers) up to several levels of animals (the consumers).
The two regimes were examined at L1 and L2 feeding levels.
Subsequent reproductive performance was not affected (P > 0.10) by feeding levels during the previous reproductive cycle.
As expected, average rumen free lysine concentrations increased linearly (P=0.05) due to increased feeding levels of lysine.
Increasing feeding levels during 3 short periods of gestation increased piglet birth weight, but did not affect piglet weaning weight.
Furthermore, piglet birth weights increased linearly (P < 0.01) with the increase of gestation feeding levels, while piglet weaning weights were similar (P > 0.10) among treatments.
Averaged over feeding levels, 5%and17%7% of the total digestible energy originated from NSP at the starch and NSP diet, respectively.
As expected, average rumen free lysine concentrations increased linearly, but only at P = 0.07, due to increased feeding levels of lysine.
Dietary treatments consisted of two concentrate feeding levels per cow (1 vs. 5 kg; as-fed basis) offered daily in equal meals during milking.
In contrast, with the rise of gestation feeding levels, lactation BW gain (14.31, 9.84, 7.09 and 3.50 kg, respectively) decreased linearly (P < 0.01), while BF loss during lactation (−0.79, −0.92, −1.12 and −1.57 mm, respectively) increased linearly (P = 0.05).
Future feeding studies with YP should consider dose response designs at YP feeding levels higher than those used in past studies, as well as report BW and BW change to allow YP response on animal energetics to be assessed.
