Production, milk iodine, and nutrient utilization in Jersey cows supplemented with the brown seaweed Ascophyllum nodosum (kelp meal) during the grazing season

Kelp meal (KM) is a supplement made from the brown seaweed Ascophyllum nodosum, known to bioaccumulate iodine (I) and to be the richest source of phlorotannins, which can inhibit ruminal proteolysis and microbial growth. The objective of this study was to investigate the effects of KM on production, milk I, concentrations of blood metabolites, apparent total-tract digestibility of nutrients, and CH4 emissions in grazing dairy cows. Eight multiparous Jersey cows averaging (mean ± SD) 175 ± 60 d in milk and 12 primiparous Jersey cows averaging 142 ± 47 d in milk at the beginning of the study were assigned to either 0 g/d of KM (control diet, CTRL) or 113 g/d of KM (brown seaweed diet, BSW) in a randomized complete block design. Diets were formulated to yield a 70:30 forage-to-concentrate ratio and consisted of (dry matter basis): 48% cool-season perennial herbage and 52% partial TMR (pTMR). Each experimental period (n = 3) lasted 28 d, with data and sample collection taking place during the last 7 d of each period. Cows had approximately 16.5 h of access to pasture daily. Herbage dry matter intake increased, and total dry matter intake tended to increase in cows fed BSW versus the CTRL diet. Milk yield and concentrations and yields of milk components were not affected by diets. Similarly, blood concentrations of cortisol, glucose, fatty acids, and thyroxine did not change with feeding CTRL or BSW. However, a diet × period interaction was observed for milk I concentration; cows offered the BSW diet had greater milk I concentration during periods 1, 2, and 3, but the largest difference between BSW and CTRL was observed in period 2 (579 vs. 111 µg/L, respectively). Except for period 2, the concentration of milk I in cows fed KM did not exceed the 500 µg/L threshold recommended for human consumption. Diet × period interactions were also found for serum triiodothyronine concentration, total-tract digestibilities of crude protein and acid detergent fiber, CH4 production, and urinary excretion of purine derivatives. Overall, the lack of KM effects on milk yield and concentrations and yields of milk components indicate that dairy producers should consider costs before making KM supplementation decisions during the grazing season. Future research is needed to evaluate the concentration of I in retail organic milk because of the high prevalence of KM supplementation in northeastern and midwestern US organic dairies and possibly in other regions of the country.

Effects of human visitation on calf growth and performance of calves fed different milk replacer feeding levels

Twenty-eight newborn Holstein heifer calves from the university herd and 8 newborn Holstein heifer calves from a commercial herd were blocked by birth and herd into 1 of 4 treatments: conventional [20% crude protein (CP), 20% fat] milk replacer (MR; treatment C) with (1) or without (0) human visitation, or a higher plane of MR nutrition (28% CP, 20% fat) regimen (treatment A) with (1) or (0) without human visitation. Calves on C MR treatments received 454 g of MR from d 2 to 41. Calves on A MR received 916 g of MR from d 2 to 8 and 1134 g of MR from d 9 to 41. Visitation with calves occurred at 1030 and 1430 h daily from d 1 to 56 and comprised verbal stimulation and stirring of starter grain. An opaque curtain divided the calf nursery, with calves in the front half assigned to visitation treatments and those in the rear half not assigned to visitation treatments. Calves were fed their MR treatment until d 43 (preweaning), after which all calves received half of their allotment of MR until d 49 (weaning). Calves were tracked for the next week until d 56 (postweaning). Starter grain and MR intakes were measured daily along with weekly body weight and skeletal measurements. One half of the calves on each treatment had blood samples taken via jugular venipuncture on d 41 (preweaning), 43, 45, 47, 49, and 51 (postweaning) to evaluate blood glucose, urea, nonesterified fatty acids, and cortisol concentrations. During the preweaning and weaning phases, calves on A0 and A1 treatments consumed more MR, less starter, and weighed more than the C0 and C1 calves. Calves on A0 and A1 had greater average daily gain (ADG), hip and withers gain, were taller at the hip, and had larger girths during the preweaning phase. Overall, body weight, withers and hip heights, and heart girths were greater in A0 andA1 calves during the weaning week. Efficiency of utilization of estimated metabolizable energy (ME) intake (ADG/ME) were similar. Glucose and nonesterified fatty acids concentrations were greater in visited calves preweaning. An interaction for glucose was observed during weaning, with A1 calves having the highest concentration and A0 calves having the lowest concentrations during weaning. Cortisol tended to be higher in visited calves during weaning. Postweaning, calves formerly fed A0 and A1 treatments had lower blood glucose and tended to have higher urea and cortisol concentrations than C0 and C1 treatments. The higher plane of nutrition fed calves tended to have higher cortisol concentrations indicating that they experienced more stress due to the removal of MR more than calves fed conventionally. Calves fed the higher plane of MR nutrition consumed more dry matter, ME, and water weighed more, had a greater ADG, and were taller than calves fed the conventional MR. These calves were more efficient (ADG/dry matter intake) when expressed on a dry matter basis, but had similar efficiency when expressed on an ME basis (ADG/ME). Visiting calves did little to reduce the stress of weaning when calves are fed the higher plane of nutrition MR feeding regimen.

Short communication: Feeding red clover cut in the afternoon or morning to late-lactation dairy cows

Forages cut in the afternoon (p.m.) generally yield a higher concentration of nonstructural carbohydrates (NSC) than those cut in the morning (a.m.). We aimed to compare the effects of p.m.-cut red clover baleage (p.m.-RC) versus a.m.-cut RC baleage (a.m.-RC) on milk yield, concentrations and yields of milk components, and apparent total-tract digestibility of nutrients in late-lactation Holstein cows. Twelve multiparous and 2 primiparous Holstein cows received a total mixed ration containing, on a dry matter (DM) basis, 65% p.m.-RC or a.m.-RC plus 35% concentrate in a crossover design with 14 d for diet adaptation and 7 d for data and sample collection. One RC field was split in 2 with the first half cut in the afternoon (1600 h) and the second half in the following morning (0600 h). The p.m.-RC and a.m.-RC contained (% of DM): 12.6 versus 9.43% NSC in samples collected before the beginning of the experiment and 7.49 versus 7.79% NSC in samples collected during the sampling periods (i.e., d 14 to 21). The total mixed rations averaged 18.2 and 17.5% NSC for the p.m.-RC and a.m.-RC, respectively. Feeding p.m.-RC or a.m.-RC did not improve feed intake or milk yield and composition in late-lactation dairy cows. However, milk urea N and plasma urea N were both lowest in cows offered p.m.-RC. With the exception of the apparent total-tract digestibility of DM, which was highest in cows fed p.m.-RC, no other changes in nutrient digestibility were observed. Similarly, no treatment effect was observed for the urinary excretion of N and purine derivatives. Further research is needed to better understand NSC losses during storage and the associated effects on baleage quality and animal performance.

Incremental amounts of Ascophyllum nodosum meal do not improve animal performance but do increase milk iodine output in early lactation dairy cows fed high-forage diets

The objective of this study was to investigate the effects of incremental amounts of Ascophyllum nodosum meal (ANOD) on milk production, milk composition including fatty acids and I, blood metabolites, and nutrient intake and digestibility in early lactation dairy cows fed high-forage diets. Twelve multiparous Jersey cows averaging (mean±standard deviation) 40±21 d in milk and 464±35 kg of body weight and 4 primiparous Jersey cows averaging 75±37 d in milk and 384±17kg of body weight were randomly assigned to treatment sequences in a replicated 4×4 Latin square design. Each period lasted 21 d with 14 d for diet adaptation and 7 d for data and sample collection. Cows were fed a total mixed ration (64:36 forage-to-concentrate ratio) supplemented (as fed) with 0, 57, 113, or 170 g/d of ANOD. Milk yield as well as concentrations and yields of milk components (fat, protein, lactose, milk urea N) were not affected by increasing dietary amounts of ANOD. Concentration (from 178 to 1,370 µg/L) and yield (from 2.8 to 20.6 mg/d) of milk I increased linearly in cows fed incremental amounts of ANOD as a result of the high concentration of I (820 mg/kg of dry matter) in ANOD. Overall, only minor changes were observed in the proportion of milk fatty acids with ANOD supplementation. Quadratic trends were observed for dry matter intake and total-tract digestibilities of organic matter and neutral detergent fiber, whereas negative linear trends were observed for serum concentration of cortisol and crude protein digestibility with ANOD supplementation. Serum concentrations of triiodothyronine and thyroxine were not affected by ANOD supplementation and averaged 1.1 and 48.4 ng/mL, respectively. However, feeding increasing amounts of ANOD linearly reduced the plasma concentration of nonesterified fatty acids (from 164 to 132 mEq/L). Quadratic effects were found for the total-tract digestibility of ADF and urinary output of purine derivatives, suggesting that ANOD supplementation may stimulate growth of ruminal cellulolytic bacteria in a dose-dependent fashion. In general, feeding incremental amounts of ANOD to early lactation dairy cows dramatically increased milk I concentration and output with no effect on animal performance.