Nitrogen utilization of lactating sows fed increasing dietary protein1

Abstract

The objectives of the study were 1) to quantify dietary N utilized for milk N and N loss in urine and feces, in sows fed increasing dietary CP with a constant amount of Lys, Met, Thr, and Trp to meet their standardized ileal digestible (SID) requirement and 2) to determine the optimal dietary CP concentration based on dietary N utilization for milk production. Seventy-two sows were fed 1 of 6 dietary treatments, formulated to increase the SID CP as followed: 11.8, 12.8, 13.4, 14.0, 14.7, and 15.6% and formulated to be isocaloric (9.8 MJ NE/kg). Diets were fed from day 2 after parturition until weaning at day 28 (± 3 d). Litters were equalized to 14 piglets and weighed within 48 h following parturition. Sows were weighed and back fat scanned, at day 18 (± 3 d) and day 28 (weaning; ± 3 d). Litter weight was recorded at day 11, 18 (± 3 d), and 28 (± 3 d). Nitrogen balances were conducted on approximately day 4, 11, and 18 (± 3 d). Daily milk yield was estimated from recorded litter gain and litter size. To calculate sows mobilization of fat and protein, body pools of fat and protein were estimated by D2O (deuterated water) enrichment on day 4 and 18 (± 3 d). No linear, quadratic, or cubic effects of increasing dietary CP was observed for sows total feed intake, sow BW, body pools of protein and fat, protein and fat mobilization, total milk yield, and piglet performance. The protein content in milk increased linearly with increasing dietary CP in week 1 (P < 0.05), week 2 (P < 0.05), and week 3 (P < 0.001). Urine production did not differ among treatments and N output in urine increased linearly with increasing dietary CP concentration in week 1 (P = 0.05), week 2 (P < 0.001), and week 3 (P < 0.001). Urine N excretion relative to N intake increased linearly with increasing dietary CP (P < 0.001). Milk N utilization relative to N intake decreased linearly from 77.8% to 63.1% from treatment 1 through 6 (P < 0.001). Corrected milk N utilization decreased from 68.6% to 64.2% from treatment 1 through 6 (P < 0.05). In conclusion, a low dietary CP concentration for lactating sows with supplemented crystalline AA improved the efficiency of dietary N utilization and reduced the N output in urine without affecting lactation performance.

Feeding sows during the transition period—is a gestation diet, a simple transition diet, or a lactation diet the best choice?1

“…Possibly the lower litter gain observed for sows fed transition diet until day 10 could be ascribed to the lower litter weight at day 2 and lower litter size at weaning (numerical differences), because both may reduce milk production and litter gain as reported by Strathe et al (2017) . Overall, the daily litter gain was fairly low (2.19 to 2.65 kg/d) when comparing with recent studies on hyper-prolific sows (3.2 to 3.3 when supplied optimally with CP; Pedersen et al, 2019a , Hojgaard et al, 2019 ), indicating that the sow milk yield was compromised. In further support of a poor milk yield, the sows indeed gained BW from day 10 and up until weaning.…”

“…Sows secreted on average 42 MJ energy, 80 g N, and 36 g Lys daily in milk from day 3 to 10 of lactation, which is considerably less than what has been found in a recent Danish study with high performing sows. In that study, sows fed increasing dietary protein from 11.8% to 15.6% SID CP secreted on average 56 MJ energy and 95 g N in milk daily during the first wk (day 4 to 11) of lactation, respectively ( Pedersen et al, 2019a , 2019b ). The milk N secretion in the current study is, however, higher than what has been reported in the study of Huber et al (2015) , where sows secreted 49 to 57 g N in milk from day 3 to 7 of lactation.…”

“…Sows in the current experiment had an average BF thickness of 12.6 to 13.9 mm at day 2 in lactation and a body fat pool of 34 to 42 kg, which is rather low compared to other Danish studies. In the study of Pedersen et al (2019b) and Pedersen et al (2019a) , sows had a BF thickness of 14.2 to 16.7 mm at day 2 in lactation and a body fat pool of 67 to 72 kg, respectively. The poor body condition of sows in the current study was likely part of the reason why sows had a low lactation performance (litter gain).…”

“…The SID N intake ( SID N intake ) was calculated as ADFI from day 3 to 10 in lactation multiplied by the estimated analyzed SID CP content in feed divided by 6.25. The daily urinary N loss (N urine ) was calculated from the following regression equation according to values adapted from Pedersen et al (2019a) :…”

Physiological and molecular aspects of ovarian follicular developmental competence in sows

“…Other possible strategies may be directed towards increasing the availability of energy and nutrients in the lactation diet, to support both follicular development during lactation and milk production. Some relatively recent studies have been directed towards feeding higher protein levels during lactation (Huang et al, 2013;Pedersen et al, 2019;.…”